* arith.c (gcd): Fix semantics. If either operand is

zero, return the other operand.
(lcm): New function.

* eval.c (eval_init): Retarget registration of gcd to
variable argument gcdv function. Register lcm.

* lib.c (gcdv, lcmv): New functions.

* lib.h (gcdv, lcm, lcmv): Declared.

* txr.1: Re-document gcd with coverage of lcm.

* txr.vim: Regenerated.

1 files changed, 18 insertions, 0 deletions

diff --git a/lib.c b/lib.c
index d25e47e3..4b929c97 100644
--- a/lib.c
+++ b/lib.c
@@ -2150,6 +2150,24 @@ val exptv(val nlist)
   return reduce_right(func_n2(expt), nlist, one, nil);
 }
 
+val gcdv(val nlist)
+{
+  if (!nlist)
+    return zero;
+  if (!cdr(nlist))
+    return abso(car(nlist));
+  return reduce_left(func_n2(gcd), nlist, colon_k, nil);
+}
+
+val lcmv(val nlist)
+{
+  if (!nlist)
+    return one;
+  if (!cdr(nlist))
+    return abso(car(nlist));
+  return reduce_left(func_n2(lcm), nlist, colon_k, nil);
+}
+
 val string_own(wchar_t *str)
 {
   val obj = make_obj();