Visual Calculus is a System Utilities software developed by GraphNow. After our trial and test, the software was found to be official, secure and free. Here is the official description for Visual Calculus: Visual Calculus is an easy-to-use software for Graphing limit, derivative function, integral, 3D vector, series, ode etc. Which can create 2D, 2.5D and 3D function graphs, animations and table graphs. 2D Features: explicit, implicit, parametric, and in equation; Cartesian and polar coordinate systems; curve and animation; graph of inverse function and derivative function; parity; maximum, minimum, and inflexion; integration; root; the length of curve; tangent and normal; curvature circle; intersection; line plot; scatter plot; stem plot; step plot; curve smoothing. 3D Features: cartesian, cylindrical, and spherical coordinate systems; 3D curve and surface; animation; 3D surface based on table data; surface by rotation; 3D vector; tangent and normal of 3D curve and surface; material and light. Ability to create color map, contour plot and vector plot. Ability to move, zoom in, zoom out and rotate graphs. Ability to save graphs as text file or bmp file. Ability to save animation as AVI file. you can download Visual Calculus free now.