If you want to create a graph, particularly a function graph, Function Grapher is a good choice. It's easy to use, can graph functions in 2D, 2.5D and 3D.

Features:

• Ability to create 2D and 3D function graphs. By extending the third dimension, 2.5D graphs of 2D functions can be created
• For 2D function, graph can be plotted in Cartesion and polar coordinate systems; for 3D function, graph can be plotted in Cartesion , cylindrical and spherical coordinate systems
• Ability to create 2D, 2.5D and 3D animations
• Ability to set and modify the color and width of 2D and 3D curves
• Ability to set and modify the color, material, model style and smoothness of 2.5D and 3D graphs
• Ability to customize the appearance of axis and the parameters of light
• Ability to save graphs as pgp format or bmp format
• Ability to cut, copy, paste and delete graph(s)
• Ability to move, zoom and rotate the scene
• Ability to render the scene view from the front, the right and the top