The InverseTransformation command uses the Maple solve command to find a (local) inverse transformation Psi: N -> M, that is, Psi o Phi = identity on M and Phi o Psi = identity on N.

Use the Maple environment variable _EnvExplicit = true to obtain explicit formulas for the inverse.

In the case where there are multiple local inverses, the first one in the list returned by solve is returned by InverseTransformation.  

With branch = "all", InverseTransformation returns a list of all the inverse transformations.

With branch = [pt1, pt2], InverseTransformation returns the particular inverse transformation Psi satisfying Psi(pt1) = pt2.

This command is part of the DifferentialGeometry package, and so can be used in the form InverseTransformation(...) only after executing the command with(DifferentialGeometry).  It can always be used in the long form DifferentialGeometry:-InverseTransformation.