untransform_gam: Transform gamma to beta polynomial coefficients
In bonStats/gcreg: General Constraint REGression

beta (b) is standard polynomial coefficients w.r.t. raw data. gamma (g) is the orthogonalised polynomial coefficients w.r.t. scaled data (-1 < x, y < 1). See transform_beta for inverse transformation.

1	untransform_gam(g, sc_x_f, sc_y_f, cv)

`g`	gamma, orthogonalised polynomial coefficients w.r.t. scaled data (-1 < x, y < 1).
`sc_x_f`	scale functions for x data created by `gen_scale_data_funs`.
`sc_y_f`	scale functions for y data created by `gen_scale_data_funs`.
`cv`	orthogonal basis converter functions created by `gen_poly_basis_converters`.