Changeset a8b44d in git for kernel/polys.cc

Timestamp:

Mar 21, 2011, 3:55:47 PM (12 years ago)

Author:

Frank Seelisch <seelisch@…>

Branches:

(u'jengelh-datetime', 'ceac47cbc86fe4a15902392bdbb9bd2ae0ea02c6')(u'spielwiese', 'a800fe4b3e9d37a38c5a10cc0ae9dfa0c15a4ee6')

Children:

9cd697732c2adbda992d49885d226fc966966251

Parents:

f4a33e267c2b5be378ef1fc5426935bee8f1e4d9

Message:

changed div check in Z/m, and command simplify over rings

git-svn-id: file:///usr/local/Singular/svn/trunk@14022 2c84dea3-7e68-4137-9b89-c4e89433aadc

File:

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

kernel/polys.cc

@@ -99 +99 @@
 * assumes that the head term of b is a multiple of the head term of a
 * and return the multiplicant *m
+* Frank's observation: If LM(b) = LM(a)*m, then we may actually set
+* negative(!) exponents in the below loop. I suspect that the correct
+* comment should be "assumes that LM(a) = LM(b)*m, for some monomial m..."
 */
 poly pDivide(poly a, poly b)
@@ -130 +133 @@
   p_Test(q, r);
   return q;
+}
+#endif
+
+static void printNumber(const number z)
+{
+  if (nIsZero(z)) printf("number = 0\n");
+  else
+  {
+    poly p = pOne();
+    pSetCoeff(p, nCopy(z));
+    pSetm(p);
+    printf("number = %s\n", pString(p));
+    pDelete(&p);
+  }
+}
+
+#ifdef HAVE_RINGS
+/* TRUE iff LT(f) | LT(g) */
+BOOLEAN pDivisibleByRingCase(poly f, poly g)
+{
+  int exponent;
+  for(int i = (int)pVariables; i; i--)
+  {
+    exponent = pGetExp(g, i) - pGetExp(f, i);
+    if (exponent < 0) return FALSE;
+  }
+  return nDivBy(pGetCoeff(g), pGetCoeff(f));
 }
 #endif
@@ -567 +597 @@
 
 /*2
-*divides p1 by its leading coefficient
+* divides p1 by its leading coefficient if it is a unit
+* (this will always be true over fields; but not over coefficient rings)
 */
 void pNorm(poly p1)
@@ -574 +605 @@
   if (rField_is_Ring(currRing))
   {
-    Werror("pNorm not possible in the case of coefficient rings.");
-  }
-  else
+    if (!nIsUnit(pGetCoeff(p1))) return;
+  }
 #endif
   if (p1!=NULL)