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Lazarus Programs and Libraries

This section has sample applications for Lazarus, possibly also usable in Delphi.

These programs are made by me and my colleagues at FEUP, possibly with code some inherited from the internet.

Absolutely no warranties!!!

Use as you wish, at your own risk :)

Armando Jorge Sousa 2008/05/22 02:00

Matrix Library

This release includes all source code and test application.

The library includes matrix function and overloaded operators for generic sized matrices. Defined operations work with matrices of variable sizes (supposedly including large sizes :-?). Operations are dimensionally protected.

The test application tests numeric precision comparing operations made my scilab and by lazarus. The numeric precision found is somewhere around 1e-6 for operations including inverting random matrices sized 6 x 6 (when comparing to scilab solutions).

The TDMatrix instances are object based which means no explicit free is necessary.

To use TDmatrix operations, just:

uses dynmatrix, dynmatrixutils;
var Mat : TDMatrix;
Mat.SetSize(2,2); // No explicit create necessary but setting the size is!
ShowMessage(FloatToString( Mat.Getv(row,col) ); 
// No explicit free is necessary

Download through Paulo Costa's wiki:

Obs: Don't forget the limited standard Lazarus library called “matrix”.

Easy DB

The program EasyDB for Lazarus tests connection to PostGreSQL database using a PQConnection component.

Includes drop table, create table, insert commands and select commands for SQL Queries.

Written by for discipline Sistemas de Informação, FEUP, Portugal

The current version includes PostGreSQL DLLs to make application standalone. These DLLs can be deleted from project directory file if PGSQL\bin is included in search path.



Includes 3 test programs that read information from files at program start and write at program exit.

They are intended to show simple control examples and they implement a name and phone number list.

They do not use any kind of DataBase, they read a file to memory.

The 3 program are:

  • Phone List with 1 list box (also demonstrates string handling)
  • Phone List with 2 list box (demonstrate several events on the list boxes)
  • Phone List with String Grid



Demo application to test Inter Process Communication. Tested in Windows and Linx.

String Grid with Combo Box and Edit in Place

Application with String Grid where a given number of columns have Edit (in place), that is, inside the grid and other number of columns have Combo Boxes.

Serial Communications Testing (sdpo component)

This demo application is a very simple serial communication tester using sdpo serial component that internally uses svasync.

It assumes a frame based communication system, start and end character are configurable.

The application should work both in Windows and Linux.

Lazarus Uninstall / Re-Install / Upgrade Problems

Just delete application settings… here is how to…

Windows: Just delete all hidden stuff:

  • %LOCALAPPDATA%\lazarus\*


  • %LOCALAPPDATA%\lazarus\environmentoptions.xml

Linux: Delete everything:

  • ~/.lazarus
  • ~root/.lazarus
  • /etc/.lazarus

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