file1: matrix_TYP containing matrices (i. e. of basis transformations or group elements)
file2: (OPTIONAL) matrix_TYP containing Gram matrices
Description
Forms the scalar product of the COLUMNS of matrices A in file1 w.r.t. the
Gram matrices F in file2, i. e. it computes Atr * F * A.
If file2 is omitted, the identity matrix is used instead.