math/mp-sqrt.c, math/pgen-granfrob.c: Publish `squarep' function.

It's not super-useful, but it fits thematically with
`mp_perfect_power_p', and publishing it is better than not.

diff --git a/debian/catacomb2.symbols b/debian/catacomb2.symbols
index a8237d8..b03dc29 100644 (file)
--- a/debian/catacomb2.symbols
+++ b/debian/catacomb2.symbols
@@ -308,6 +308,7 @@ libcatacomb.so.2 catacomb2 #MINVER#
 
 ## mp-modsqrt
        mp_modsqrt@Base 2.2.0
+       mp_squarep@Base 2.6.99~
 
 ## mp-fibonacci
        mp_fibonacci@Base 2.1.3

diff --git a/math/mp-sqrt.c b/math/mp-sqrt.c
index bf19fe8..9530ff9 100644 (file)
--- 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

diff --git a/math/mp.h b/math/mp.h
index 23e71e3..75dfd5b 100644 (file)
--- a/math/mp.h
+++ b/math/mp.h
@@ -923,6 +923,16 @@ extern mp *mp_leastcongruent(mp */*d*/, mp */*b*/, mp */*r*/, mp */*m*/);
 
 extern mp *mp_sqrt(mp */*d*/, mp */*a*/);
 
+/* --- @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 %$a$%.
+ */
+
+extern int mp_squarep(mp */*n*/);
+
 /* --- @mp_nthrt@ --- *
  *
  * Arguments:  @mp *d@ = fake destination

diff --git a/math/pgen-granfrob.c b/math/pgen-granfrob.c
index 98c8f8c..0516539 100644 (file)
--- a/math/pgen-granfrob.c
+++ b/math/pgen-granfrob.c
@@ -36,16 +36,6 @@
 
 /*----- Main code ---------------------------------------------------------*/
 
-static int 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);
-}
-
 /* --- @pgen_granfrob@ --- *
  *
  * Arguments:  @mp *n@ = an integer to test
@@ -103,7 +93,7 @@ int pgen_granfrob(mp *n, int a, int b)
     e = mp_jacobi(&md, n);
 
     /* If %$\Delta$% is a perfect square then the test can't work. */
-    if (e == 1 && squarep(&md)) { rc = PGEN_ABORT; goto end; }
+    if (e == 1 && mp_squarep(&md)) { rc = PGEN_ABORT; goto end; }
   } else {
     /* Determine parameters.  Use Selfridge's `Method A': choose the first
      * %$\Delta$% from the sequence %$5$%, %$-7$%, %%\dots%%, such that
@@ -113,7 +103,7 @@ int pgen_granfrob(mp *n, int a, int b)
     wa = 1; wd = 5;
     for (;;) {
       e = mp_jacobi(&md, n); if (e != +1) break;
-      if (wd == 25 && squarep(n)) { rc = PGEN_FAIL; goto end; }
+      if (wd == 25 && mp_squarep(n)) { rc = PGEN_FAIL; goto end; }
       wd += 2; md.f ^= MP_NEG;
     }
     a = 1; d = wd;