a # 1 65 R 'z # a index b                                                    '
a # a,[1]  '"index - column index in matrix b whose members all belong to a  '
a # a,[1]  '"from ''the apl handbook of techniques'' copyright 1978, ibm.      '
a # a,[1]  '"-returns the index position of each column of b all of whose    '
a # a,[1]  '" elements are in a.  b must be a matrix.  the shaps of a is     '
a # a,[1]  '" not restricted.  the arguments may be either character or      '
a # a,[1]  '" numeric.                                                       '
a # a,[1]  ' z#(&`/bEa)/I1URb                                                '
Lfx a