MFP Newton Solver

This app uses Newton-Raphson method to solve one variable expression which equals to zero. Note that the expression and its variable are both string based. The initial guess of the variable is 0, max number of steps is 50 and error tolerance is 10e-8. For example,
newtonSolver("x**2+2*x-9", "x")
returns 2.1622777. If there is no real result for the variable, this function throws an exception.
Note that this app was developed by an easy-to-learn and cross-platform scripting language called MFP. This language's IDE is an Android application called Scientific Calculator Plus.