`inv'
-----

inv(I,M)
     :: M $@$rK!$H$9$k(J I $@$N5U?t(J

RETURN
     $@@0?t(J
I,M
     $@@0?t(J

   * IA == 1 mod (M) $@$J$k@0?t(J A $@$r5a$a$k(J.
   * I $@$H(J M $@$O8_$$$KAG$G$J$1$l$P$J$i$J$$$,(J, `inv()' $@$O$=$N%A%'%C%/$O9T(J
     $@$o$J$$(J.

     [71] igcd(1234,4321);  
     1
     [72] inv(1234,4321);
     3239
     [73] irem(3239*1234,4321);
     1

$@;2>H(J
     `igcd'

