Posted by
Leniel Macaferi
on
6/19/2008 01:10:00 AM
The crescent demand for enterprise management software has as key factor big companies, which need to manage millions of records trying with that: find a better way of working with so great amount of information available in their huge databases and get to the target of their business.
Between the most used software for enterprise management are the ones that lie in one of the following main categories:
Resources planning in a company (ERP) include or try to include all the company’s data and processes in a unified system. A typical ERP system will use multiple software and hardware components to achieve integration. A key ingredient for most ERP system is the use of a unified database to store the data from the various modules of the system.
CRM
Customer relationship management uses software products developed to help the companies in the construction and keeping of a good relationship with their clients. This is done through the storage of information of each client in an efficient and intelligent way. CRM is a general term that encompasses concepts used by the companies to manage their clients and includes capture, storage and analysis of data, suppliers, partners and internal processes information.
SCM
Supply chain management is the process of planning, implementing and controlling the operations of the supply chain to the highest efficiency degree possible. SCM includes all the transport logistics and storage of raw material and ready products from the origin to the destiny consumption market.
BSC
Balanced scorecard or scoreboard is a concept used to measure if the activities of a company are yielding expected results in terms of the strategic vision. Its focus isn’t only the financial result but also human questions. It helps in the provisioning of a more comprehensive vision of an organization what in its turn helps the companies to act according to the best way possible in a long term basis.
How is it used?
All these software work integrated.
The chairman, VP, CFO, CEO, CIO, CTO, etc., simply sat down in front of their computer and request a report. The systems then combine the data stored in unified databases, which have all the company’s historical data using technologies such as OLAP and OLTP. Business intelligence (BI), artificial intelligence (AI), data mining, etc, are concepts extensively applied to do the junction of enterprise data.
It has all to do with relevant data and how to better combine them through (SQL queries) to extract useful information. Information = processed data = money! :-)
My computer engineering final project verses about LINQ (Language Integrated Query), that is, the integration of the query language (SQL) into the programming language (specifically C#). It's a good starting point for those that wanna learn the principles of working with queries to extract useful information from databases.
What to expect from the future?
The good part of it is that this market is growing in a fast pace. This way, a lot of job opportunities are emerging.
I particularly have interest in this field: databases, computer networks, BI, HPC, etc. My area of specialization will be for sure system analysis with focus on software engineering and infrastructure.
I expect to work in this field in a near future. It’s really interesting and challenging because there are always details that can be improved, optimized.
Information management (IM) is the key to the proper organization of a company. If a company organizes its data, its income will grow. It’s a proved fact.
Just as a note: one alarming factor that can arise is the security related to all the information of a company what creates the field of information security.
A new area that is attracting attention nowadays is parallel computing, most precisely, high performance computing, which is other very important factor when dealing with huge sets of data as is the case of enterprise management software.
Parallel processing will be the focus on the next years because it is necessary for the next step toward fastest software processing. Long live the dual-quad (many) core processors.
Posted by
Leniel Macaferi
on
5/20/2008 07:03:00 PM
This post is related to one of the best coursework I've done during the computer engineering course. I'm really proud of it. It was the cornerstone in my programming career and helped me choose an area to put my efforts from that moment on. I was in the 5th term out of 10 (3rd year of the course out of 5 more exactly). The discipline was Programming Languages.
This subject is fantastic and is used extensively throughout the the computer science field.
First I'll give a short description about the Quicksort and Binary Search algorithms and then I'll present the work that I and my dear brother in faith Wellington Magalhães Leite did.
Quicksort
Quicksort is a well-known sorting algorithm developed by C. A. R. Hoare. Typically, quicksort is significantly faster in practice than other sorting algorithms, because its inner loop can be efficiently implemented on most architectures.
Binary Search
A binary search algorithm (or binary chop) is a technique for finding a particular value in a sorted list. It makes progressively better guesses, and closes in on the sought value by selecting the median element in a list, comparing its value to the target value, and determining if the selected value is greater than, less than, or equal to the target value. A guess that turns out to be too high becomes the new top of the list, and a guess that is too low becomes the new bottom of the list. Pursuing this strategy iteratively, it narrows the search by a factor of two each time, and finds the target value.
Our paper
Our paper is entitled Quicksort and Binary Search Algorithms. You can get a copy at the end of this post.
Without more ado, see its abstract bellow:
Sorting and searching algorithms are a core part of the computer science area. They are used throughout the programming work when you need to sort a set of data and when you need to search for a specific record (key) present in such set of data.
Quicksort is one of the fastest (quick) sorting algorithms and is most used in huge sets of data. It performs really well in such situations.
Binary search tree is one of the fastest searching algorithms and is applied in a sorted set of data. It reduces the search space by 2 in each iteration, hence its name (binary).
In this paper we present the intrinsic nature of each algorithm as well as a functional implementation of such algorithms in the C++ programming language.
Keywords: quicksort, binary search, sorting algorithms, searching algorithms, c++ programming language
CONTENTS
1 INTRODUCTION 6
1.1 Objective 6
1.2 Definition 6
1.2.1 Sorting algorithms 6
1.2.2 Searching algorithms 7
2 DEVELOPMENT 8
2.1 Quicksort algorithm (swapping and partitioning) 8
2.1.1 Detailed steps 8
2.2 Binary search algorithm 9
2.3 Studying the efficiency of the methods 9
2.3.1 The big O notation 9
2.3.2 Quicksort efficiency 10
2.3.2.1 The best and the worst case 10
2.3.2.2 Comparison with other sorting algorithms 11
2.3.3 Binary search efficiency 11
3 APPLICATION 12
3.1 Quicksort implementation 12
3.2 Binary search implementation 13
4 CONCLUSION 14
5 REFERENCES 15
Words of wisdom
As I mentioned, during the 5th term of the computer engineering course our teacher Marcus Vinicius Carvalho Guelpeli selected some sorting and searching algorithms to pass to the class as a coursework.
The coursework should be done in pairs and each pair should select a sorting and searching algorithm to compose a paper about it. We selected the quicksort and the binary search algorithms. The teacher advised us that these weren't the easy ones. I just thought: that's what I want. I don't want the easy ones. Why? Because if you get just the easy problems I'll never understand something that demands a more deep approach and every time a difficult task is given you'll tend to refuse it. What's the best thing to do? Just accept the challenge and go for it. Chances are you'll succeed. That's just what happened with us.
We haven't just written about the quicksort and the binary search, we implemented it and presented it to the class in a power point presentation. The teacher liked it so much that our grade was the highest possible! :-) In the end what did we feel? An amazing feeling. Something such that the work had been done and we learned a lot from it. That's what a college is supposed to do. Give you the subjects and motivate you; teaching the basic so that you can dig up the more difficult aspects of the subject being taught.
So what's next? Well, I'll explain how we implemented the quicksort and the binary search algorithms.
Quicksort and Binary search algorithms implementation in C++
One of the things that I've always listened to was about code reuse. You search for something already implemented so that you just haven't to reinvent the wheel. Of course you'll complement or even adapt the available code to your situation. That was what we did. I found some code for the quick sort at MSDN and implemented the binary search one. Unfortunately the page at MSDN isn't available anymore. It's been three years since I hit that page.
I wanted a way of measuring the time elapsed so that we could compare the efficiency of both methods when they were fed with different input data sets. The input is nothing more than a text file .txt full of numbers in this case. Can be any data you want. Each test case we passed a text file with different random numbers and different quantity of numbers. For example, in a test case we passed a file named 2500.txt, that means 2500 random numbers. In another test case we passed other file named 7500.txt as so on. I think you got it. Doing so we could compare how well the algorithms were performing.
To generate the random numbers we used an Excel spreadsheet with the formula =RAND()*1000000. For each set of data we generated new numbers and copied and pasted those numbers into the text files that are the input for our program. During a coursework as this one we get to learn everywhere, even a new formula in Excel. It's really good. ;-)
Again, I searched for a timing class that I could reuse with the code and for sure I found it. I didn't use it at all but I used it to learn about how to measure time in C++. It's amazing how fast you can implement something. Much of the things you need related to programming are already implemented. You just have to search for it as is what you're doing here, I think! You searched for the subject of this post and here you are seeing something implemented. Try to learn from it and just don't copy the entire work and think that you know about it. It's wrong. Try to understand what the code is doing. Dive into the theory because it explains the inner essence.
The code that follows is well commented which is something every developer should do. You see, it was three years ago when we worked with this code. Today it's difficult to remember every step I took. The comments helped me to remember almost everything.
Bellow I present the quick sort method we borrowed from MSDN (we adapted it to fit our case). Note the use of the Partition method (explained in the accompanying paper):
// QuickSort implementation
void QuickSort(char** szArray, int nLower, int nUpper)
{
// Check for non-base case
if(nLower < nUpper)
{
// Split and sort partitions
int nSplit = Partition(szArray, nLower, nUpper);
QuickSort(szArray, nLower, nSplit - 1);
QuickSort(szArray, nSplit + 1, nUpper);
}
}
// QuickSort partition implementation
int Partition (char** szArray, int nLower, int nUpper)
{
// Pivot with first element
int nLeft = nLower + 1;
char* szPivot = szArray[nLower];
int nRight = nUpper;
// Partition array elements
char* szSwap;
while(nLeft <= nRight)
{
// Find item out of place
while(nLeft <= nRight && strcmp (szArray[nLeft], szPivot) <= 0)
nLeft = nLeft + 1;
while (nLeft <= nRight && strcmp (szArray[nRight], szPivot) > 0)
nRight = nRight - 1;
// Swap values if necessary
if(nLeft < nRight)
{
szSwap = szArray[nLeft];
szArray[nLeft] = szArray[nRight];
szArray[nRight] = szSwap;
nLeft = nLeft + 1;
nRight = nRight - 1;
}
}
// Move pivot element
szSwap = szArray[nLower];
szArray[nLower] = szArray[nRight];
szArray[nRight] = szSwap;
return nRight;
}
Now see the binary search method implementation that we did:
int BinarySearch(char** szArray, char key[], int nLower, int nUpper)
{
// Termination case
if(nLower > nUpper)
return 0;
int middle = (nLower + nUpper) / 2;
if(strcmp(szArray[middle], key) == 0)
return middle;
else
{
if(strcmp(szArray[middle], key) > 0)
// Search left
return BinarySearch(szArray, key, nLower, middle - 1);
// Search right
return BinarySearch(szArray, key, middle + 1, nUpper);
}
}
The next ones are the method prototypes and the main entry point that calls a menu. According to the user passed parameters we call the quicksort and the binary search methods:
// Function prototypes
void Menu(void);
void QuickSort(char** szArray, int nLower, int nUpper);
int Partition(char** szArray, int nLower, int nUpper);
int BinarySearch(char** szArray, char key[], int nLower, int nUpper);
// Application initialization
void main(void)
{
char op;
do
{
Menu();
printf("\n\nDo you wanna a new QuickSort? Y/N");
op = getche();
if(islower(op))
op = toupper(op);
}
while(op == 'Y');
}
void Menu(void)
{
// Clear screen
system("CLS");
// Control execution time
clock_t initial, final;
// Print startup banner
printf("\nQuickSort C++ Sample Application\n");
printf("Copyright (c)2001-2002 Microsoft Corporation. All rights reserved.\n\n");
printf("MSDN ACADEMIC ALLIANCE [http://www.msdnaa.net/]\n\n");
printf("BinarySearch C++ Sample Application\n");
printf("Copyright (c)2005 Leniel Braz de Oliveira Macaferi & Wellington Magalhaes Leite.\n");
printf("UBM COMPUTER ENGINEERING - 5TH SEMESTER [http://www.ubm.br/]\n\n");
// Describe program function
printf("This program example demonstrates the QuickSort and BinarySearch algorithms by\n");
printf("reading an input file, sorting its contents, writing them to a new file and\n");
printf("searching on them.\n\n");
// Prompt user for filenames
char szSrcFile[1024], szDestFile[1024];
printf("Source: ");
gets(szSrcFile);
printf("Output: ");
gets(szDestFile);
// Read contents of source file
const long nGrow = 8;
long nAlloc = nGrow;
long nSize = 0;
char** szContents = new char* [nAlloc];
char szSrcLine[1024];
FILE* pStream = fopen(szSrcFile, "rt");
while(fgets(szSrcLine, 1024, pStream))
{
// Trim newline character
char* pszCheck = szSrcLine;
while(*pszCheck != '\0')
{
if(*pszCheck == '\n' && *(pszCheck + 1) == '\0')
*pszCheck = '\0';
pszCheck++;
}
// Append to array
szContents[nSize] = new char [strlen(szSrcLine) + 1];
strcpy(szContents[nSize], szSrcLine);
nSize = nSize + 1;
if(nSize % nGrow == 0)
{
// Resize the array
char** szPrev = szContents;
nAlloc += nGrow;
szContents = new char* [nAlloc];
memcpy(szContents, szPrev, nSize * sizeof(char*));
delete szPrev;
}
}
fclose (pStream);
initial = clock();
// Pass to QuickSort function
QuickSort(szContents, 0, nSize - 1);
final = clock();
// Write sorted lines
pStream = fopen (szDestFile, "wt");
for(int nIndex = 0; nIndex < nSize; nIndex++)
{
// Write line to output file
fprintf (pStream, "%s\n", szContents[nIndex]);
}
fclose (pStream);
// Report program success
printf("\nThe sorted lines have been written to the output file.\n\n");
// QuickSort execution time
double duration = (double)(final - initial) / CLOCKS_PER_SEC;
printf("The QuickSort execution time was: %2.9lf s = %.0lf ms = %.0lf \xE6s\n\n", duration, duration * 1000, duration * 1000000);
char op = '\0';
do
{
printf("Do you wanna a BinarySearch to locate a specific key? Y/N");
op = getche();
if(islower(op))
op = toupper(op);
if(op == 'Y')
{
printf("\n\nType the key you want to search for: ");
char key[1024];
gets(key);
initial = clock();
if(BinarySearch(szContents, key, 0, nSize - 1))
{
final = clock();
duration = (double)(final - initial) / CLOCKS_PER_SEC;
printf("\nKey found!\n\n");
printf("The BinarySearch execution time was: %2.9lf s = %.0lf ms = %.0lf \xE6s\n\n", duration, duration * 1000, duration * 1000000);
}
else
{
final = clock();
duration = (double)(final - initial) / CLOCKS_PER_SEC;
printf("\nKey not found!\n\n");
printf("The BinarySearch execution time was: %2.9lf s = %.0lf ms = %.0lf \xE6s\n\n", duration, duration * 1000, duration * 1000000);
}
}
else
{
// Deallocate entire array
for(int nIndex = 0; nIndex < nSize; nIndex++)
// Delete current array element
delete szContents[nIndex];
delete szContents;
szContents = NULL;
}
}
while(op == 'Y');
}
Enter the name of a file that contains unsorted data;
Use the sample files included in the .ZIP package as: 1000.txt and 2500.txt;
In the command line "Source", type: 1000.txt;
In the command line "Output", type a name to the file that will be sorted. e.g.: sorted.txt;
After the sorting process, choose if you want or not to execute a Binary Search. If yes, provide a value to be searched. If not, choose if it is or not desired to execute a new Quicksort.
Postscript:
- To generate random numbers, use the file Random numbers generator.xls file;
- The file QuicksortBinarySearch.cpp contains the source code. The same can be used freely. Mention the authors.
Efficiency comparison
For the sake of comparison I've run some test cases with different input files. See the result in the table that follows:
Quicksort and Binary search performance
n
File name
File size (bytes)
Timing (milliseconds)
Quicksort
Binary search
10000
10000.txt
122.880
16
0
25000
25000.txt
200.704
78
0
50000
50000.txt
401.408
219
0
75000
75000.txt
602.112
360
0
100000
100000.txt
802.816
516
0
It's important to note that the time the quicksort takes appears to be longer but it is not. Why? Because the the program needs to read the file content and write the sorted data back to the output file so that it appears to take longer than the milliseconds shown on the above table. The timing functions just operate while the quicksort is running.
For the the binary search key I've input a value localized in the beginning of the sorted file, in the middle and in the end. There was no time changes. The binary search found the key I entered with a time less than (0 µs - microsecond). I have an AMD Athlon XP 2400 with 512 MB RAM.
Posted by
Leniel Macaferi
on
5/03/2008 07:23:00 PM
Windows API The Windows API, informally WinAPI, is Microsoft's core set of application programming interfaces (APIs) available in the Microsoft Windows operating systems. All Windows programs except console programs must interact with the Windows API regardless of the language.
Win32 API The Win32 API is the 32-bit API for modern versions of Windows. The API consists of functions implemented, as with Win16, in system DLLs. The core DLLs of Win32 are kernel32.dll, user32.dll, and gdi32.dll. Win32 was introduced with Windows NT.
Words of wisdom Dealing with the Win32 API appears to be a regression since it takes us to the last century, that is, when programming with such API we are writing code that resembles the code written 15 years ago or more. Regression was the feeling I felt when the teacher said we'd study this API. Nevertheless, there are billions of lines of code that need maintenance because great part of these lines are used in legacy systems. So you see that learning this API is fundamental even today. This is in contrast with the mainframe computers dilemma. Even today there are a bunch of companies that still use them because of legacy systems. The feeling of regression was substituted by a enthusiasm one in the end.
Mouse interaction app One coursework related to the Object Oriented Systems discipline I had to develop was a program that draws on the screen by free hand with the mouse assistance. The program must monitor the mouse movement, indicating its position (x, y) in the upright corner of the application window, in the format (xxx, yyy). Pressing the left mouse button it draws and pressing the right mouse button, it wipes off the screen content.
Some valuable tips that the teacher gave: Use the events WM_MOUSE, WM_LBUTTONDOWN, WM_LBUTTONUP, WM_RBUTTONDOWN, WM_RBUTTONUP and the function SetPixel()
lword(lParam) has 0 x hiword(lParam) has 0 Y
I originally implemented this program using DevC++. Today while composing this post I just created a new Win32 Project application using the Microsoft Visual Studio C++ Express Edition. Although the implementation differs a little bit, it wasn't difficult to port it to the Microsoft programming environment. I'll provide both implementations at the end of the post.
Let's see the mouse app main block of code. It's inside the WndProc function that is responsible for processing the messages for the main window. The code is commented so I think it's unnecessary to add more to it.
// // FUNCTION: WndProc(HWND, UINT, WPARAM, LPARAM) // // PURPOSE: Processes messages for the main window. // // WM_COMMAND - Process the application menu // WM_PAINT - Paint the main window // WM_DESTROY - Post a quit message and return // WM_LBUTTONDOWN - Left mouse button clicked // WM_RBUTTONDOWN - Right mouse button clicked // WM_LBUTTONUP - Left mouse button released // WM_RBUTTONUP - Right mouse button released // WM_MOUSEMOVE - Controls the mouse movement // LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) { int wmId, wmEvent;
switch(message) //Handle the messages { case WM_DESTROY:
PostQuitMessage(0); // Send a WM_QUIT to the message queue
break;
case WM_PAINT: // TODO: Add any drawing code here... hDC = GetDC(hWnd);
BeginPaint(hWnd, &paintStruct);
EndPaint(hWnd, &paintStruct);
break;
// Left button event used to print the screen case WM_LBUTTONDOWN:
flag = true;
// Black color newColor = RGB(0, 0, 0);
xMouse = LOWORD(lParam);
yMouse = HIWORD(lParam);
SetPixel(hDC, xMouse, yMouse, newColor);
break;
// Right button event used to erase the screen content case WM_RBUTTONDOWN:
flag = true;
// White color newColor = RGB(255, 255, 255);
xMouse = LOWORD(lParam);
yMouse = HIWORD(lParam);
SetPixel(hDC, xMouse, yMouse, newColor);
break;
// Sets the flag to false so that we know the left mouse button was released case WM_LBUTTONUP:
flag = false;
break;
// Sets the flag to false so that we know the right mouse button was released case WM_RBUTTONUP:
flag = false;
break;
// Controls the mouse movement and shows its current position on the Window title case WM_MOUSEMOVE:
Posted by
Leniel Macaferi
on
5/01/2008 06:17:00 PM
Following the coursework related to the Compilers Construction discipline I attended during the Computer Engineering course, I was asked to indent and capitalize the reserved words (keywords) of a source code file. More specifically, to do this work I should use the Syntactic Analyzer built with Flex and YACC that was created in a previous coursework task.
The source code file in question is the one being analyzed by the syntactic analyzer. This way at the same time it analyses the syntactic structure of the file it also indents and capitalizes the keywords.
The following is the content of the syntactic analyzer file named sinan.yacc:
%{
#include <stdio.h>
#include <stdlib.h>
int c;
%}
%token PROGRAM
%token ID
%token SEMIC
%token DOT
%token VAR
%token COLON
%token INTEGER
%token REAL
%token RCONS
%token BOOL
%token OCBRA
%token CCBRA
%token IF
%token THEN
%token ELSE
%token WHILE
%token DO
%token READ
%token OPAR
%token CPAR
%token WRITE
%token COMMA
%token STRING
%token ATRIB
%token RELOP
%token ADDOP
%token MULTOP
%token NEGOP
%token CONS
%token TRUE
%token FALSE
%%
prog : PROGRAM {printf("PROGRAM "); c = 0;}
ID {printf("%s", yytext);}
SEMIC {printf(";\n\n");}
decls
compcmd
DOT {printf(".");}
{
printf("\n Syntactical Analisys done without erros!\n");
return 0;
}
;
decls : VAR {printf("VAR ");} decl_list
;
decl_list : decl_list decl_type
decl_type
;
decl_type : id_list COLON {printf(":");} type SEMIC {printf(";\n");}
;
id_list : id_list COMMA {printf(", ");} ID {printf("%s", yytext);}
ID {printf("%s", yytext);}
;
type : INTEGER {printf(" INTEGER");}
REAL {printf(" REAL");}
BOOL {printf(" BOOL");}
;
compcmd : OCBRA {int i; for(i = 0; i < c; i++)printf(" "); printf("{\n"); c = c + 2;} cmd_list CCBRA {printf("\n"); int i; for(i = 2; i < c; i++)printf(" "); printf("}"); c = c - 2;}
;
cmd_list : cmd_list SEMIC {printf(";\n\n");} cmd
cmd
;
cmd : {int i; for(i = 0; i < c; i++)printf(" ");} If_cmd
{int i; for(i = 0; i < c; i++)printf(" ");} While_cmd
{int i; for(i = 0; i < c; i++)printf(" ");} Read_cmd
{int i; for(i = 0; i < c; i++)printf(" ");} Write_cmd
{int i; for(i = 0; i < c; i++)printf(" ");} Atrib_cmd
compcmd
;
If_cmd : IF {printf("IF ");} exp THEN {printf(" THEN\n");} cmd Else_cmd
;
Else_cmd : ELSE {printf("\n"); int i; for(i = 0; i < c; i++)printf(" "); printf("ELSE\n"); c = c + 2;} cmd {c = c - 2;}
;
While_cmd : WHILE {printf("WHILE ");} exp DO {printf(" DO\n");} cmd
;
Read_cmd : READ {printf("READ");} OPAR {printf("(");} id_list CPAR {printf(")");}
;
Write_cmd : WRITE {printf("WRITE");} OPAR {printf("(");} w_list CPAR {printf(")");}
;
w_list : w_list COMMA {printf(", ");} w_elem
w_elem
;
w_elem : exp
STRING {printf("%s", yytext);}
;
Atrib_cmd : ID {printf("%s ", yytext);} ATRIB {printf("= ");} exp
;
exp : simple_exp
simple_exp RELOP {printf(" %s ", yytext);} simple_exp
;
simple_exp : simple_exp ADDOP {printf(" %s ", yytext);} term
term
;
term : term MULTOP {printf(" %s ", yytext);} fac
fac
;
fac : fac NEGOP {printf(" %s", yytext);}
CONS {printf(" %s", yytext);}
RCONS {printf(" %s", yytext);}
OPAR exp CPAR
TRUE {printf("TRUE ");}
FALSE {printf("FALSE ");}
ID {printf("%s", yytext);}
;
%%
#include "lex.yy.c"
As you can see there is an integer variable named c right beneath the #include section. This variable is incremented and decremented according to the section of code being analyzed (parsed). Such variable is then used inside the for loops. According to its current value blank spaces are written on the screen so that the next token parsed is printed on the right position (indented).
Each keyword parsed is capitalized and printed on the screen through a simple printf command.
Let's run a simple test case with the following source code file named test.txt. The code is intentionally not indented and it doesn't do much. It's just for a testing purpose.
program factorial;
var n, fact, i: integer;
{
read(n);
fact = 1;
i = 1;
while i <= n do
{
fact = fact * i;
i = i + 1
};
if i >= fact then
{
i = fact;
fact = fact + 1
}
else
i = fact + 1;
if i < fact then
{
i = fact;
fact = fact + 1
};
write("The factorial of ", n, " is: ", fact)
}.
In blue are the keywords, so the output should present them in CAPITALIZED letters. The blocks of code should also be presented with indentation according to the logic specified above. I use 2 white spaces to indent the blocks of code. That's why I use c = c + 2 (to increment) and c = c - 2 (to decrement) the c variable is responsible for controlling the indentation.
To run the test case it's necessary to build the syntactic analyzer. I won't show here all the steps involved since it's already done in the paper described in the post Syntactic Analyzer built with Flex and YACC. So I'll just compile the sinan.yacc file since it's the only file that was modified to accomplish this task. The other necessary files to generate the executable file - such as the lexical analyzer ones - are included in the download package at the end of this post.
For a better understanding of the commands used in this post and to set up the development environment I recommend that you read at least section 3.3 of the paper Syntactic Analyzer built with Flex and YACC. That said, let's do the job. :-)
To run this test case, follow the steps listed bellow:
Create a folder called IndentCapCode on the root directory C:\, which will contain all the files created henceforward.
Open a command prompt and type: path=C:\MinGW\bin;%PATH%. I consider that the MinGW installation was done in the folder C:\MinGW. Change it accordingly. After completing this step the tools to build the syntactic analyzer will be available in the command prompt.
Generate the file y.tab.c in the command prompt with following command: yacc sinan.yacc.
Compile the files with GCC in the command prompt with the following command: gcc y.tab.c yyerror.c main.c -osinan -lfl.
The result file for the syntactic analyzer is sinan.exe. To use it just type sinan < test.txt. The file test.txt contains the source code to be analyzed by the syntactic analyzer.
You can see the commands listed above in action through the following screenshot:
In a next post related to compilers construction I'll show the implementation of a semantic analyzer. This implementation was another coursework task. I used the same principle shown here to indent the code and even to colorize the keywords. But this is for another day.
Note: if you want, you can use a batch file (.bat) to automate the steps listed above. A .bat file named ini.bat is included in the .ZIP package. For more information about batch files, read my previous post Programming-Constructing a Batch file.
Posted by
Leniel Macaferi
on
4/27/2008 08:23:00 PM
Distance education or distance learning is a positive manner of tackling global education shortcomings. If we think about the world population we can imagine that not everyone has easy access to the resources we’re so accustomed to. Considering time constraints, distance education reveals itself a great alternative because the time spent to get to a classroom can be a negative factor. Think about people that live outside of big cities. They can't even apply for a course they want because there is no such a course where they live. These barriers lessen education availability and so someone somewhere that doesn’t fit on the above time and place prerequisites has their plans thwarted and can't move forward towards the mainstay “Education”. It’s a really beautiful word. Look at it for an instant and realize what would be of you if you didn’t have the basic of it. To those people to acquire a diploma in some area of knowledge can be considered an unthinkable action.
With the advent of the Internet we have today a classroom right inside our own home. We have the information we want at the exact moment we want and in most part all the information is freely available, that is, we have the opportunity to learn about any subject without having to pay for that end avoiding expenses with specific material that in most cases will be used only once or at most twice to be frank.
Obviously there are prestigious institutions that provide distance education, which confer the most prestigious titles to those that finish a course without at least being present in a classroom. All that with the help of new technological advances that pervade our lives, which in turn make distance education something viable.
Particularly I don’t like the idea of distance education. I prefer to be present at the classroom. I believe that presence education is more enriching. I write this based upon all point of views, being the most important: more active social life interaction.
The virtual classroom world is interesting, yet it’s necessary to heed, for this can bring some undesirable consequences such as the lack of a direct liaison between the teacher/professor and their students and colleagues. Great part of our development is done through social interaction and this is almost foregone when we talk about distance education. There are plenty of other factors that influence my opinion, but for now this demonstrates one of the big bottlenecks that refrains the distance education of evolving in faster paces. There are still conservatives. It can be the case that in a near future such conservatives perish the thought.
The actual distance education environments, such as TelEduc in Brazil enable the distance education practice to reach more and more people. My alma mater UBM constituted a center for distance education called NEAD and uses TelEduc as its environment. I have used it and what I write here has as background my experience as a user of the system.
Tertiary institutions as the case of UBM offer a vast range of improvement courses for their employees and even support courses for students that are undergoing their internship programs and college conclusion projects. The idea appears to be good, but in practice it’s not adopted by everyone, perhaps because of the lack of information regarding the distance education platform’s features and capabilities.
It’s good to highlight that the devices and techniques used to implement distance education are in great part the result of advances pertaining to information and communication technologies. These technologies aggregate people from the more diverse knowledge fields. Information and communication technologies include the set of technological and computational resources set aside to generate and propitiate the use of information. Thus, such technologies are established on the following components: hardware and their peripheral devices, software and their resources, telecommunication systems and data and information management.
The people responsible for the development and management of these components are increasingly requested on the market. Between them are computer engineers, computer scientists, system analysts, business analysts, chief information officers (CIO), chief executive officers (CEO), chief financial officers (CFO) just to name a few.
The instructional level has been growing a lot during the last years, what rises the competitiveness on the job market. A proven fact is that executives have been using distance education to leverage their academic degree, attending courses, such as a Master of Business Administration (MBA) at international universities as MIT, University of Cambridge, University of California, Berkeley, etc. Notwithstanding the executives are on their houses in the comfort of their couches or beds.
I complete this brief analysis of the influence of distance education stating that the use of new technologies like the Internet and well developed distance education environments are making life a lot easier if we take into account the commodity and easy access to information of any given area.
It’s worth to remember about the inherited risks that most of the times pass by unnoticed. The utilization of technology in excess can enslave men, transforming them in slaves of their own inventions. Wherefore we must discuss such subject, aiming at the discovery of a steady point between the virtual and real life, providing a better way for a rich development environment where all people can evolve in a natural manner. I wrote and meant everybody, what presupposes the integration of the underprivileged people into this whole new world of information called Internet. Long live the blogs of life.
Posted by
Leniel Macaferi
on
4/21/2008 07:29:00 AM
Compilers construction paper I and a dear brother in faith of mine called Wellington Magalhães Leite wrote a paper titled: A Syntactic Analyzer built with the CASE tools Flex and YACC
See the paper's abstract below:
The function of a syntactic analyzer in a compiler is to verify the syntactic structure of a program’s source code. It then detects, signalize and handle the syntactic errors found in the source code and at the same time servers as the framework for the front-end (user interface) of the program. So, its construction helps with the familiarization regarding the tasks included in the compiler project.
The language used in this paper does not have left recursion. The language neither presents subprograms, nor indexed variables and its only loop command is while for the sake of simplicity. The syntactic analyzer implemented uses the bottom-up parsing approach.
This paper presents the steps to the construction of a syntactic analyzer, which serves as a base element for a compiler implementation.
Posted by
Leniel Macaferi
on
4/19/2008 12:57:00 AM
Computer graphics paper I and a dear brother in faith of mine called Wellington Magalhães Leite wrote a paper titled: Influence of Tonal and Spatial Resolution on the Image File Size
See the original image we used to perform the tests regarding our paper:
The paper is accompanied by a spreadsheet and both are available in English and Portuguese.
See the paper's abstract below (English/Portuguese):
ABSTRACT
It is interesting to notice how the three variables (bits per pixel, number of colors and image file size) discussed in this paper are extremely related.
More and more we express ourselves through the use of images, which consequently need a place to be stored and this has to do with their usage in digital mediums as is the case of the Internet; take the Flickr service as an example. The storage is made in a digital form, that is, in bits.
It is known that: the better the image quality, the bigger will be the number of bits per pixel that are used to compose the image, what makes us capable of visualizing a great number of colors (tonal resolution), for the number of colors is coupled up to the quantity of bits per pixel. If we increase the number of pixels (spatial resolution) of the image, the generated file size will be bigger, in other words, more bits will be consumed to compose the image and depending on this value, the distribution or visualization of the image can be inadequate in certain conditions.
So, we can perceive the necessity of a case by case study, looking for a suitable value to the three variables, what will provide us with an ideal image file for each type of job.
Keywords: computer graphics, tonal resolution, spatial resolution, bits per pixel, number of colors, image file size
CONTENTS
1 INTRODUCTION 6
1.1 Objective 6
1.2 Definition 6
1.3 Tonal resolution 7
1.4 Spatial resolution 7
2 DEVELOPMENT 8
2.1 Image edition 8
2.1.1 Creating the work directory 8
2.1.2 Obtaining the data “bits” for the experiment 8
2.1.3 Selecting only the image of interest 8
2.1.4 Opening the test file with Photoshop 9
2.1.5 Visualizing the image size properties 10
2.1.6 Redefining the image size 11
2.1.7 Saving the modified image 12
2.1.8 Producing images with different spatial resolution 13
2.1.9 Altering the tonal resolution 13
2.1.10 Returning to Windows Paint 14
2.1.11 Producing images with different tonal resolutions 15
3 APPLICATION 16
3.1 24, 16, 8, 4 and 1 bit tonal resolutions 16
3.2 Tonal resolution vs. Spatial resolution vs. Image size 20
4 CONCLUSION 22
5 REFERENCES 23
RESUMO
É interessante notar como as três variáveis (bits por pixel, número de cores e tamanho do arquivo de imagem) discutidos neste trabalho estão intensamente relacionadas.
Cada vez mais nos expressamos através de imagens, as quais necessitam conseqüentemente de um local para serem armazenadas, haja vista a utilização em meio digital. Veja o site Flickr por exemplo. O armazenamento por sua vez é feito de forma digital, ou seja, através de bits.
É sabido que quanto maior for a qualidade da imagem, maior será o número de bits por pixel utilizados na composição da mesma, o que nos possibilita a visualização de um grande número de cores (resolução tonal), pois o número de cores está atrelado à quantidade de bits por pixel. Se aumentamos o número de pixels (resolução espacial) da imagem, maior será o tamanho do arquivo gerado, ou seja, mais bits serão consumidos para armazenar a imagem e dependendo deste valor, a distribuição ou visualização da imagem pode se tornar inadequada em certas condições.
Percebe-se então a necessidade de um estudo caso a caso, em busca de um valor adequado para essas três variáveis, de modo a obter um arquivo de imagem ideal para cada tipo de trabalho.
Palavras-chave: computação gráfica, resoulução tonal, resolução espacial, bits por pixel, número de cores, tamanho do arquivo de imagem
SUMÁRIO
1 INTRODUÇÃO 7
1.1 Objetivo 7
1.2 Definição 7
1.3 Resolução tonal 8
1.4 Resolução espacial 8
2 DESENVOLVIMENTO 9
2.1 Edição de imagens 9
2.1.1 Criando a pasta de trabalho 9
2.1.2 Obtendo os dados “bits” para o experimento 9
2.1.3 Selecionando somente a imagem de interesse 9
2.1.4 Abrindo o arquivo de teste com o Photoshop 10
2.1.5 Visualizando as propriedades do tamanho da imagem 11
2.1.6 Redefinindo o tamanho da imagem 12
2.1.7 Salvando a imagem modificada 13
2.1.8 Produzindo imagens com diferentes resoluções espaciais 15
2.1.9 Alterando a resolução tonal 15
2.1.10 Retornando ao Paint do Windows 15
2.1.11 Produzindo imagens com diferentes resoluções tonais 16
3 APLICAÇÃO 17
3.1 Resoluções tonais de 24, 16, 8, 4 e 1 bit 17
3.2 Resolução tonal vs. Resolução espacial vs. Tamanho do arquivo 21
4 CONCLUSÃO 23
5 BIBLIOGRAFIA 24
See the PivotChart created with the spreadsheet data:
You can get a PDF copy of the paper and the accompanying Excel spreadsheet at:
Posted by
Leniel Macaferi
on
4/15/2008 02:19:00 AM
One of the last computer engineering course works I had to do was to code a simple Java application. This application should use a database to store and retrieve its data. The discipline was Advanced Computing Topics. The teacher Luís Henrique Campos Braune sent the class an e-mail explaining what he wanted us to do. The following lines are a transcript of what he wanted us to do initially.
The basic idea was that we would study a sample java application1, a very simple one, and starting with it we would program another one. The work would be done in teams and the teacher orientation was that we should only use the allotted class time because we were also preparing our computer engineering final project and he didn't want us to spend time at home with course work related to his discipline. He thought that the time allotted to the classes would be sufficient for this task.
1The sample Java application can be downloaded at the end of this post. The initial code and instructions were written in Portuguese. I translated all the code and instructions to the English language, so that it can reach a broader audience.
We didn't use an Integrated Development Environment (IDE) to work with it. All the preliminary changes to the code was done using a simple text editor as the Windows Notepad. The purpose of this application was to introduce the students to the object oriented programming world based on windows and user events. We should compile and run it according to the following steps:
1st step - Download and decompress the .zip file provided by the teacher.
The sample application should be uncompressed in the root dir C:\ on the classroom computer to facilitate the work.
The following table shows the content of the .zip file:
.ZIP file content
File
Description
MainMenu.java
Class pertaining to the main menu
ClientRecord.java
Class pertaining to Retrieve/Change/Save/Delete client
VideoRecord.java
Class pertaining to Retrieve/Change/Save/Delete video
VideoRental.java
Class pertaining to video rental
VideoDevolution.java
Class pertaining to video devolution
DatabaseAccess.java
Class pertaining to the database connection and functions
VideoRentalStore.mdb
Microsoft Access database file
README.txt
A read me file with instructions
2nd step - Compile the sample app To do this we should open a command prompt, navigate to the sample app directory and type: javac MainMenu.java
In case the above command didn't work for you, refer to the The Java Platform section bellow.
3rd step - Run the sample app After compiling the the Sample app it's necessary to run the same. To do this, again in the command prompt, type: java MainMenu
In both cases it's important to type observing UPPER and lower case letters. It's case sensitive.
If the 2nd step above didn't work, we have two possibilities:
- The JDK is installed but not configured
A simple tip to see if the JDK is already installed is to look for some version of the JDK in "C:\Program files\Java"; if there is a version but on trying to compile you get an error, then you need to configure it first. That's what we'll do in the Installing the Java Development Kit section bellow.
- The JDK isn't installed
There are different "editions" of the Java Platform, including:
Java ME (Micro Edition): Specifies several different sets of libraries (known as profiles) for devices which are sufficiently limited that supplying the full set of Java libraries would take up unacceptably large amounts of storage.
Java SE (Standard Edition): For general purpose use on desktop PCs, servers and similar devices.
The one that would fit our necessity was the J2SE edition without the NetBeans IDE, that is usually offered with the Java Platform when you download it.
There are several flavors, each one suitable for a specific type of operating system. For this post I used the Windows offline installation file called jdk-6u2-windows-i586-p.exe (65.5 MB).
Installing the Java Development Kit The following are the steps we used to install the JDK. It's really easy! You practically have to click on next, next and next.
Just pay attention to the fact that, after the installation of the JDK, the JRE will also be installed in case you don't have it.
The trick is to configure the Java Platform after the JDK has been installed. To do that, check where the installation was done. Usually it is in C:\Proram files\Java\jdk...
Now, right click on My computer, Properties, Advanced tab, Environment variables. Click on New variable. Can be in User variables or System variables. Create the two variables according to the following table:
Environment variables
Variable
Name
Value
1
CLASSPATH
;.;C:\Program files\Java\jdk1.6.0_02
2
PATH
;C:\Program files\Java\jdk1.6.0_02\bin
Notes: - A dot (.) is part of the CLASSPATH variable value. - The path here presented are for mere illustration. What really matter is the current path you have on your computer. - Each value has a semicolon in its beginning. - I used the value jdk1.6.0_02 because this is the JDK version I have on my machine. This explains why I used ... to point the JDK installation path. If you have a different version, make the appropriate change.
Save everything clicking OK.
To test if the Java Platform was installed/configured correctly, try to compile and run the sample application executing the 1st and 2nd steps of The Java Sample Application section above.
Configuring the database connection It wasn't enough for our Java sample application. We then should configure the database, more precisely, the alias used to reference the Microsoft Access VideoRentalStore.mdb database file.
What we needed to do was to create an ODBC connection so that the database file would be referenced through the alias used within the DatabaseAccess.java source code file. To do this we should do the following:
Go to Control Panel, Administrative Tools, ODBC Data Sources, click on the Add connection and choose Microsoft Access driver; in data source name value we should type the alias "VideoRentalStore" used in the DatabaseAccess.java source code file and in Database we should select/point to the VideoRentalStore.mdb database file that is inside the uncompressed directory.
Doing so we should be able to Retrieve/Change/Save/Delete data using the sample application.
Any doubts should be reported to the teacher. That's what he's there for, right?!
OK that was the first class we had and so is the first post in this series.
Next post in this series Come back to see a next post in which I'll start to drill down what I particularly did, that is, what path I followed to take advantage of and master my skills while developing the other version of such application.
Get the Java Video Rental Store sample application at:
The crescent demand for enterprise management software has as key factor big companies, which need to manage millions of records trying with that: find a better way of working with so great amount of information available in their huge databases and get to the target of their business.
The chairman, VP, CFO, CEO, CIO, CTO, etc., simply sat down in front of their computer and request a report. The systems then combine the data stored in unified databases, which have all the company’s historical data using technologies such as OLAP and OLTP. Business intelligence (BI), artificial intelligence (AI), data mining, etc, are concepts extensively applied to do the junction of enterprise data.
