perldl> p $a=sequence(5)
[0 1 2 3 4]
perldl> p $b=pdl(1,4,9,9,16)
[1 4 9 9 16]

**** To get the index of values in $a that can be found anywhere in $b: 

perldl> $d=which(maximum (($a==$b->dummy)->xchg(0,1))!=0)

perldl> p $d
[1 4]