Do you need to draw graphs. There are many applications but I personally like the “Graph” Freeware Application. Graph is an open source application (GNU GPL). So you will get the full software for FREE. You can easily draw your mathematical graphs with this application. You can give a mathematical function and a graph will be created for you. You can even paste this graph in other applications.
With Graph you can draw a graph for many built-in functions like sin, cos, tan, log etc. You can draw graphs for normal, parameter and polar functions. You can set different color, line style and other parameters for your graph. You can save the file in different formats like BMP, JPEG and PDF. You can also copy the graph to other programs like Microsoft Word or PowerPoint as an image or OLE object. There are really a lot of options for you to apply for your graph. I was able to create some simple functions and draw graphs or that very easily.
Graph is working fine on my Vista machine. it also works for Windows 98, Windows ME, Windows 2000 and Windows XP. Even it is a Windows application you can use Wine to run it on Linux.