[bug-gawk] GAWK 4.1.60 DIV() Remainder Bug

[Katherine Wasserman]

In version 4.1.60 of GAWK the div() function returns remainders that seem
wrong, or at least inconsistent with the standard mod (%) function.
This only happens with negative numerators.  Programming languages
vary on the proper way to deal with this, so I'm not going to suggest
that one calculation or the other is correct.  However the behavior
for bignums and regular integers should at least be the same.

Here's a demo of the problem:

Running this program (remainder.awk):
--------------------------------------------------------------------
BEGIN {
test(15,7)
test(-15,7)
test(15,-7)
test(-15,-7)
}


function test(x,y, r)
{
  print x,y ":"
  print "normal quotient " int(x/y)
  print "normal remainder " x%y

  div(x,y,r)
  for (i in r)
    print "bignum " i " "
r[i]

}

--------------------------------------------------------------------
gawk -M -f remainder.awk

results in:
15 7:
normal quotient 2
normal remainder 1
bignum quotient 2
bignum remainder 1
-15 7:
normal quotient -2
normal remainder 6
bignum quotient -2
bignum remainder -1
15 -7:
normal quotient -2
normal remainder 1
bignum quotient -2
bignum remainder 1
-15 -7:
normal quotient 2
normal remainder 6
bignum quotient 2
bignum remainder -1


Thanks,
Katie