Changeset 1fc83c0 in git for Singular/longrat.cc

Timestamp:

Aug 12, 1997, 7:14:45 PM (27 years ago)

Author:

Hans Schönemann <hannes@…>

Branches:

(u'fieker-DuVal', '117eb8c30fc9e991c4decca4832b1d19036c4c65')(u'spielwiese', 'fc741b6502fd8a97288eaa3eba6e5220f3c3df87')

Children:

457e2d7f256604a4b31c642f360b63b13a5151cb

Parents:

573ae7acc2dadf68863ca5ee07211c1e9a07b3fb

Message:

* hannes:
  added nExactDiv to numbers
   (numbers.*, longrat.*)
 corrected open bug in sing_dbm.cc (could only "r")
 simplified sing_dbm.cc (many tests already in silink.cc)
   (sing_dbm.cc, silink.h)
 added "mod" (as an alias to "%")
   (iparith.cc)
 updated singular.doc: div/mod, DBM: links
 ANSI-conversion in ndbm.cc (added return types, include files)


git-svn-id: file:///usr/local/Singular/svn/trunk@614 2c84dea3-7e68-4137-9b89-c4e89433aadc

File:

• Singular/longrat.cc (modified) (2 diffs)

Singular/longrat.cc

@@ -2 +2 @@
 *  Computer Algebra System SINGULAR     *
 ****************************************/
-/* $Id: longrat.cc,v 1.10 1997-08-08 12:59:22 obachman Exp $ */
+/* $Id: longrat.cc,v 1.11 1997-08-12 17:14:39 Singular Exp $ */
 /*
 * ABSTRACT: computation with long rational numbers (Hubert Grassmann)
@@ -1227 +1227 @@
 
 /*2
+* u := a / b in Z, if b | a (else undefined)
+*/
+number   nlExactDiv(number a, number b)
+{
+  if (b==INT_TO_SR(0))
+  {
+    WerrorS("div. by 0");
+    return INT_TO_SR(0);
+  }
+  number u;
+  if (SR_HDL(a) & SR_HDL(b) & SR_INT)
+  {
+    /* the small int -(1<<28) divided by -1 is the large int (1<<28)   */
+    if ((a==INT_TO_SR(-(1<<28)))&&(b==INT_TO_SR(-1)))
+    {
+      return nlRInit(1<<28);
+    }
+    int aa=SR_TO_INT(a);
+    int bb=SR_TO_INT(b);
+    return INT_TO_SR(aa/bb);
+  }
+  number bb=NULL;
+  if (SR_HDL(b) & SR_INT)
+  {
+    bb=nlRInit(SR_TO_INT(b));
+    b=bb;
+  }
+  u=(number)Alloc(sizeof(rnumber));
+#ifdef LDEBUG
+  u->debug=123456;
+#endif
+  mpz_init(&u->z);
+  /* u=a/b */
+  u->s = 3;
+  MPZ_EXACTDIV(&u->z,&a->z,&b->z);
+  if (bb!=NULL)
+  {
+    mpz_clear(&bb->z);
+    Free((ADDRESS)bb,sizeof(rnumber));
+  }
+  if (mpz_size1(&u->z)<=MP_SMALL)
+  {
+    int ui=(int)mpz_get_si(&u->z);
+    if ((((ui<<3)>>3)==ui)
+    && (mpz_cmp_si(&u->z,(long)ui)==0))
+    {
+      mpz_clear(&u->z);
+      Free((ADDRESS)u,sizeof(rnumber));
+      u=INT_TO_SR(ui);
+    }
+  }
+#ifdef LDEBUG
+  nlTest(u);
+#endif
+  return u;
+}
+
+/*2
 * u := a / b in Z
 */