Changeset 7b4bfe6 in git for factory/fac_util.cc

Timestamp:

Jul 8, 1996, 10:22:02 AM (28 years ago)

Author:

Rüdiger Stobbe <stobbe@…>

Branches:

(u'spielwiese', 'fe61d9c35bf7c61f2b6cbf1b56e25e2f08d536cc')

Children:

db4770670387300daebce8262e6dddb3e3ba4b7f

Parents:

f63dbca24fdad0fc65e8496a781d6830dafded8e

Message:

"New organization of the factorization stuff. Some functions moved from
fac_diophand.cc which no longer exists.
"


git-svn-id: file:///usr/local/Singular/svn/trunk@40 2c84dea3-7e68-4137-9b89-c4e89433aadc

File:

• factory/fac_util.cc (modified) (4 diffs)

factory/fac_util.cc

@@ -1 +1 @@
 // emacs edit mode for this file is -*- C++ -*-
-// $Id: fac_util.cc,v 1.1 1996-06-27 11:34:24 stobbe Exp $
+// $Id: fac_util.cc,v 1.2 1996-07-08 08:22:02 stobbe Exp $
 
 /*
 $Log: not supported by cvs2svn $
+Revision 1.1  1996/06/27 11:34:24  stobbe
+"New function dviremainder.
+"
+
 Revision 1.0  1996/05/17 10:59:46  stobbe
 Initial revision
@@ -11 +15 @@
 #include "assert.h"
 #include "cf_defs.h"
+#include "canonicalform.h"
+#include "cf_iter.h"
 #include "fac_util.h"
 
@@ -144 +150 @@
 
 CanonicalForm
+maxCoeff( const CanonicalForm & f )
+{
+    if ( f.inCoeffDomain() )
+        return abs( f );
+    else {
+        CanonicalForm M = 0, m;
+        for ( CFIterator i = f; i.hasTerms(); i++ )
+            if ( (m = maxCoeff( i.coeff() )) > M )
+                M = m;
+        return M;
+    }
+}
+
+
+CanonicalForm
 mappksymmetric ( const CanonicalForm & f )
 {
@@ -158 +179 @@
     return mod( f, PK );
 }
+
+void
+extgcd ( const CanonicalForm & a, const CanonicalForm & b, CanonicalForm & S, CanonicalForm & T, const modpk & pk )
+{
+    int p = pk.getp(), k = pk.getk(), j;
+    CanonicalForm amodp, bmodp, smodp, tmodp, s, t, sigma, tau, e;
+    CanonicalForm modulus = p, sigmat, taut, q;
+
+    setCharacteristic( p );
+    {
+        amodp = mapinto( a ); bmodp = mapinto( b );
+        (void)extgcd( amodp, bmodp, smodp, tmodp );
+    }
+    setCharacteristic( 0 );
+    s = mapinto( smodp ); t = mapinto( tmodp );
+
+    for ( j = 1; j < k; j++ ) {
+        e = ( 1 - s * a - t * b ) / modulus;
+        setCharacteristic( p );
+        {
+            e = mapinto( e );
+            sigmat = smodp * e;
+            taut = tmodp * e;
+            divrem( sigmat, bmodp, q, sigma );
+            tau = taut + q * amodp;
+        }
+        setCharacteristic( 0 );
+        s += mapinto( sigma ) * modulus;
+        t += mapinto( tau ) * modulus;
+        modulus *= p;
+    }
+    S = s; T = t;
+}
+