Freehand Function Tool
From GeoGebra Manual
The Freehand Function Tool lets you sketch a function. Once a function is created, you can compute its value at certain point, place a point on it or perform some transformations. Derivatives for these functions are not supported (tangents are supported as a numerical approximation)
Notes:
- You can use all the curve fitting commands on functions created by this Tool, e.g. FitSin_Command
- You can use the Integral command on functions created with this tool e.g.
Integral[f, 1, 5]to shade under it and find the area
