a # 1 60 R ' r#diff a                                                   '
a # a,[1]  ' r#((_RRa)Y-1)U(1`Oa)_a                                     '
a # a,[1]  ' $0                                                         '
a # a,[1]  '"diff - differences between adjacent elements.              '
a # a,[1]  '"from ''the apl handbook of techniques'' copyright 1978, ibm. '
a # a,[1]  '"-a is any numeric structure.                               '
a # a,[1]  '"-r has one fewer columns than a, and consists of the       '
a # a,[1]  '" successive differences, a[..;..;i+1]_a[..;..;i]           '
Lfx a