FPlot is a freeware program to plot and fit functions. Functions are entered as C# code. This way you can express any function and the functions evaluate at an optimal speed. You can also integrate and differentiate numerically in your functions. You can even use other numerical .NET libraries. Thus FPlot is an easy but very flexible, extensible and fast plotting and curve fitting software. FPlot also comes with a .NET library that implements the core functionality of FPlot and that you can use in your own .NET programs. You can even include a function plot in an ASP.NET webpage.