GAP Manual: 48.28. InverseClassesCharTable

InverseClassesCharTable( tbl )

returns the list mapping each class of the character table tbl to its inverse class. This list can be regarded as (-1)-st powermap; it is computed using tbl.irreducibles.

    gap> InverseClassesCharTable( CharTable( "L3(2)" ) );
    [ 1, 2, 3, 4, 6, 5 ]