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-rw-r--r--array.c14
1 files changed, 10 insertions, 4 deletions
diff --git a/array.c b/array.c
index 674e354..e131d1f 100644
--- a/array.c
+++ b/array.c
@@ -5079,10 +5079,16 @@ permute0(const long n, const long r, long *const p, char *const used, const VALU
static VALUE
descending_factorial(long from, long how_many)
{
- VALUE cnt = LONG2FIX(how_many >= 0);
- while (how_many-- > 0) {
- VALUE v = LONG2FIX(from--);
- cnt = rb_int_mul(cnt, v);
+ VALUE cnt;
+ if (how_many > 0) {
+ cnt = LONG2FIX(from);
+ while (--how_many > 0) {
+ long v = --from;
+ cnt = rb_int_mul(cnt, LONG2FIX(v));
+ }
+ }
+ else {
+ cnt = LONG2FIX(how_many == 0);
}
return cnt;
}