X-Git-Url: https://git.distorted.org.uk/~mdw/catacomb/blobdiff_plain/6af2607b63ce649a919513949d5f8a8deb2e6663..d2679863cf27b0812a4b88397be1ebf0b1319305:/math/mp-sqrt.c

diff --git a/math/mp-sqrt.c b/math/mp-sqrt.c
index bf19fe8e..9530ff99 100644
--- a/math/mp-sqrt.c
+++ b/math/mp-sqrt.c
@@ -126,6 +126,24 @@ mp *mp_sqrt(mp *d, mp *a)
   return (d);
 }
 
+/* --- @mp_squarep@ --- *
+ *
+ * Arguments:	@mp *n@ = an integer
+ *
+ * Returns:	Nonzero if and only if @n@ is a perfect square, i.e.,
+ *		%$n = a^2$% for some rational integer %$a$%.
+ */
+
+int mp_squarep(mp *n)
+{
+  mp *t = MP_NEW;
+  int rc;
+
+  if (MP_NEGP(n)) return (0);
+  t = mp_sqrt(t, n); t = mp_sqr(t, t);
+  rc = MP_EQ(t, n); mp_drop(t); return (rc);
+}
+
 /*----- Test rig ----------------------------------------------------------*/
 
 #ifdef TEST_RIG