Changeset fd80670 in git for factory/facFqBivarUtil.cc

Timestamp:

Nov 29, 2012, 4:39:48 PM (11 years ago)

Author:

Martin Lee <martinlee84@…>

Branches:

(u'jengelh-datetime', 'ceac47cbc86fe4a15902392bdbb9bd2ae0ea02c6')(u'spielwiese', '0604212ebb110535022efecad887940825b97c3f')

Children:

fe969a75147c2bf74dfb88f8b9b8ee94e2557a20

Parents:

c49e6ff67dcc4fd9d834166f973fd81fbc6cec2b

git-author:

Martin Lee <martinlee84@web.de>2012-11-29 16:39:48+01:00

git-committer:

Martin Lee <martinlee84@web.de>2012-11-30 17:25:33+01:00

Message:

fix: bug in divrem2 and logDeriv

File:

• factory/facFqBivarUtil.cc (modified) (2 diffs)

factory/facFqBivarUtil.cc

@@ -504 +504 @@
     CanonicalForm G3= div (G, xToOldL);
     CanonicalForm Up= mulMod2 (G3, oldQ, xToLOldL);
-    CanonicalForm xToOldL2= power (x, oldL/2);
+    CanonicalForm xToOldL2= power (x, (oldL+1)/2);
     CanonicalForm G2= mod (G, xToOldL);
     CanonicalForm G1= div (G2, xToOldL2);
@@ -510 +510 @@
     CanonicalForm oldQ1= div (oldQ, xToOldL2);
     CanonicalForm oldQ0= mod (oldQ, xToOldL2);
-    CanonicalForm Mid= mulMod2 (G1, oldQ1, xToLOldL);
+    CanonicalForm Mid;
+    if (oldL % 2 == 1)
+      Mid= mulMod2 (G1, oldQ1*x, xToLOldL);
+    else
+      Mid= mulMod2 (G1, oldQ1, xToLOldL);
     //computation of Low might be faster using a real middle product?
     CanonicalForm Low= mulMod2 (G0, oldQ1, xToOldL)+mulMod2 (G1, oldQ0, xToOldL);
-    Low= div (Low, xToOldL2);
+    Low= div (Low, power (x, oldL/2));
+    Low= mod (Low, xToLOldL);
     Up += Mid + Low;
     bufF= div (F, xToOldL);