X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=blobdiff_plain;f=check%2Ftime_vandermonde.cpp;h=17fa65bacc541acfe774745065858f5d1f78d129;hp=6473856957c2f857b70a9f310767b22aff4abb94;hb=e2627379c98aeafae903cc2f04bdbdc9defa34f7;hpb=ae3044935ddf13dd325f6e11770357b99bbe6095;ds=sidebyside

diff --git a/check/time_vandermonde.cpp b/check/time_vandermonde.cpp
index 64738569..17fa65ba 100644
--- a/check/time_vandermonde.cpp
+++ b/check/time_vandermonde.cpp
@@ -7,7 +7,7 @@
  */
 
 /*
- *  GiNaC Copyright (C) 1999-2000 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2003 Johannes Gutenberg University Mainz, Germany
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -29,34 +29,39 @@
 static unsigned vandermonde_det(unsigned size)
 {
 	unsigned result = 0;
-	symbol a("a");
-	
+	const symbol a("a");
+
 	// construct Vandermonde matrix:
 	matrix M(size,size);
 	for (unsigned ro=0; ro<size; ++ro) {
 		for (unsigned co=0; co<size; ++co) {
 			if (ro%2)
-				M.set(ro,co,pow(-pow(a,1+ro/2),co));
+				M(ro,co) = pow(-pow(a,1+ro/2),co);
 			else
-				M.set(ro,co,pow(pow(a,1+ro/2),co));
+				M(ro,co) = pow(pow(a,1+ro/2),co);
 		}
 	}
-	
+
 	// compute determinant:
-	ex vdet = M.determinant();
-	
-	// dirty consistency check of result:
-	if (!vdet.subs(a==1).is_zero()) {
+	ex det = M.determinant();
+
+	// check the result:
+	ex vanddet = 1;
+	for (unsigned i=0; i<size; ++i)
+		for (unsigned j=0; j<i; ++j)
+			vanddet *= M(i,1) - M(j,1);
+
+	if (expand(det - vanddet) != 0) {
 		clog << "Determaint of Vandermonde matrix " << endl
 		     << "M==" << M << endl
-		     << "was miscalculated: det(M)==" << vdet << endl;
+		     << "was miscalculated: det(M)==" << det << endl;
 		++result;
 	}
-	
+
 	return result;
 }
 
-unsigned time_vandermonde(void)
+unsigned time_vandermonde()
 {
 	unsigned result = 0;
 	
@@ -67,10 +72,10 @@ unsigned time_vandermonde(void)
 	vector<double> times;
 	timer swatch;
 	
-	sizes.push_back(4);
 	sizes.push_back(6);
 	sizes.push_back(8);
 	sizes.push_back(10);
+	sizes.push_back(12);
 	
 	for (vector<unsigned>::iterator i=sizes.begin(); i!=sizes.end(); ++i) {
 		int count = 1;