Changeset 1e579c6 in git for kernel/rmodulo2m.cc

Timestamp:

Jun 20, 2007, 11:39:25 AM (17 years ago)

Author:

Oliver Wienand <wienand@…>

Branches:

(u'spielwiese', 'fe61d9c35bf7c61f2b6cbf1b56e25e2f08d536cc')

Children:

07e8ae3b1877436cb95506c90d799438d558c703

Parents:

f7aaec31bd73e9e5b3b2bd84ee5ff4fab2de4691

Message:

kutil.cc:
* use nExtGcd, nIsUnit
* extended spolys only for non-domains

numbers.cc, numbers.h, structs.h:
* new Functions: nIsUnit, nGetUnit, nExtGcd
* new Field: the Integers

polys.cc, polys.h:
* nGetUnit hack removed
* minor memory glitch

polys1.cc:
* no pContent for Integers

ring.h:
new rField methos for Integers and p^n

rintegers.*:
implementation of the whole numbers using gmp

rmodulo*:
added funcs: nIsUnit, nGetUnit, nExtGcd


git-svn-id: file:///usr/local/Singular/svn/trunk@10125 2c84dea3-7e68-4137-9b89-c4e89433aadc

File:

• kernel/rmodulo2m.cc (modified) (4 diffs)

kernel/rmodulo2m.cc

@@ -2 +2 @@
 *  Computer Algebra System SINGULAR     *
 ****************************************/
-/* $Id: rmodulo2m.cc,v 1.11 2007-05-23 07:47:31 wienand Exp $ */
+/* $Id: rmodulo2m.cc,v 1.12 2007-06-20 09:39:25 wienand Exp $ */
 /*
 * ABSTRACT: numbers modulo 2^m
@@ -80 +80 @@
 }
 
+/*
+ * Give the largest non unit k, such that a = x * k, b = y * k has
+ * a solution.
+ */
+number nr2mExtGcd (number a, number b, number *s, number *t)
+{
+  NATNUMBER res = 0;
+  if ((NATNUMBER) a == 0 && (NATNUMBER) b == 0) return (number) 1;
+  while ((NATNUMBER) a % 2 == 0 && (NATNUMBER) b % 2 == 0)
+  {
+    a = (number) ((NATNUMBER) a / 2);
+    b = (number) ((NATNUMBER) b / 2);
+    res++;
+  }
+  if ((NATNUMBER) b % 2 == 0)
+  {
+    *t = NULL;
+    *s = nr2mInvers(a);
+    return (number) ((1L << res));// * (NATNUMBER) a);  // (2**res)*a    a ist Einheit
+  }
+  else
+  {
+    *s = NULL;
+    *t = nr2mInvers(b);
+    return (number) ((1L << res));// * (NATNUMBER) b);  // (2**res)*b    b ist Einheit
+  }
+}
+
 void nr2mPower (number a, int i, number * result)
 {
@@ -126 +154 @@
 {
   return nr2mSubM(a,b);
+}
+
+BOOLEAN nr2mIsUnit (number a)
+{
+  return ((NATNUMBER) a % 2 == 1);
+}
+
+number  nr2mGetUnit (number k)
+{
+  if (k == NULL) 
+    return (number) 1;
+  NATNUMBER tmp = (NATNUMBER) k;
+  while (tmp % 2 == 0)
+    tmp = tmp / 2;
+  return (number) tmp;
 }
 
@@ -372 +415 @@
   else
   {
-    WarnS("nInitChar failed");
+    WarnS("nInitExp failed");
   }
 }