Graph Plotter and Equation Parser
Graph plotter is a C program. The UI is used with iGraphics. It can implement one variable function f(x) in 2 dimensional and three variable function f(x, y) in 3 dimensional space.
You can also use
Equation parser.c as a parser completely written in C.
The program runs in Visual Studio. So the environment needs to be set up first.
The procedure is described in the zipped folder.