SDL2 Grid, graph equations, graphics calculator ( 1.1 )
- graphs algebraic functions and evaluates expressions
- zoom in/out, shift left/right, up/down of the graph
- prevents invalid input from being entered into expression ( example: can't press decimal . twice to get .. which is always invalid)
- in general similar design to windows calculator
- add functions (sin, cos, etc)
- show zoom/shift variables, and x & y values on graph
( ...eventually start over and make a 3d graph calculator with opengl)
