Updated libs from the Adaptagrams project: libavoid, libcola and libvspc; changed the code to match the new API

Signed-off-by: Sylvain Chiron <chironsylvain@orange.fr>

1 files changed, 73 insertions, 51 deletions

diff --git a/src/libcola/conjugate_gradient.cpp b/src/libcola/conjugate_gradient.cpp
index 67d15d6a0..adb7fa67f 100644
--- a/src/libcola/conjugate_gradient.cpp
+++ b/src/libcola/conjugate_gradient.cpp
@@ -1,32 +1,60 @@
-#include <math.h>
-#include <stdlib.h>
-#include <valarray>
-#include <cassert>
-#include "conjugate_gradient.h"
-
 /*
-* Authors:
-*   Nathan Hurst <njh@njhurst.com>
-*   Tim Dwyer <tgdwyer@gmail.com>
-*
-* Copyright (C) 2006 Authors
-*
-* Released under GNU LGPL.
+ * vim: ts=4 sw=4 et tw=0 wm=0
+ *
+ * libcola - A library providing force-directed network layout using the 
+ *           stress-majorization method subject to separation constraints.
+ *
+ * Copyright (C) 2006  Nathan Hurst <njh@njhurst.com>
+ * Copyright (C) 2006-2008  Monash University
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ * See the file LICENSE.LGPL distributed with the library.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  
+ *
+ * Author(s):  Nathan Hurst
+ *             Tim Dwyer
+ *            
 */
 
+
+#include <cmath>
+#include <cstdlib>
+#include <cassert>
+#include <valarray>
+
+#include "libvpsc/assertions.h"
+#include "libcola/commondefs.h"
+#include "libcola/conjugate_gradient.h"
+
 /* lifted wholely from wikipedia.  Well, apart from the bug in the wikipedia version. */
 
 using std::valarray;
 
 static void 
 matrix_times_vector(valarray<double> const &matrix, /* m * n */
-		    valarray<double> const &vec,  /* n */
-		    valarray<double> &result) /* m */
+            valarray<double> const &vec,  /* n */
+            valarray<double> &result) /* m */
 {
     unsigned n = vec.size();
     unsigned m = result.size();
-    assert(m*n == matrix.size());
+    COLA_ASSERT(m*n == matrix.size());
+#   if defined(_MSC_VER)
+    // magmy: The following lines show how operator[] is defined for valarray under MSVC
+    // _Ty valarray<_Ty>::operator[](size_t _Off) const;
+    // _Ty &valarray<_Ty>::operator[](size_t _Off);
+    // As a consequence, it is not possible to take the address of a constant valarray[n].
+    // This looks like a bug in the Microsoft's <valarray> file.
+    // Below is a workaround
+    double const *mp = &const_cast<valarray<double> &>(matrix)[0];
+#   else
     const double* mp = &matrix[0];
+#   endif
     for (unsigned i = 0; i < m; i++) {
         double res = 0;
         for (unsigned j = 0; j < n; j++)
@@ -50,66 +78,60 @@ inner(valarray<double> const &x,
     return total;// (x*y).sum(); <- this is more concise, but ineff
 }
 
-void 
-conjugate_gradient(double **A, 
-                   double *x, 
-                   double *b, 
-                   unsigned n, 
-                   double tol,
-                   unsigned max_iterations) {
-    valarray<double> vA(n*n);
-    valarray<double> vx(n);
-    valarray<double> vb(n);
-    for(unsigned i=0;i<n;i++) {
-        vx[i]=x[i];
-        vb[i]=b[i];
-        for(unsigned j=0;j<n;j++) {
-            vA[i*n+j]=A[i][j];
+double compute_cost(valarray<double> const &A, 
+        valarray<double> const &b,
+        valarray<double> const &x,
+        const unsigned n) {
+    // computes cost = 2 b x - x A x
+    double cost = 2. * inner(b,x);
+    valarray<double> Ax(n);
+    for (unsigned i=0; i<n; i++) {
+        Ax[i] = 0;
+        for (unsigned j=0; j<n; j++) {
+            Ax[i] += A[i*n+j]*x[j];
         }
     }
-    conjugate_gradient(vA,vx,vb,n,tol,max_iterations);
-    for(unsigned i=0;i<n;i++) {
-        x[i]=vx[i];
-    }
+    return cost - inner(x,Ax);
 }
 void 
 conjugate_gradient(valarray<double> const &A, 
-		   valarray<double> &x, 
-		   valarray<double> const &b, 
-		   unsigned n, double tol,
-		   unsigned max_iterations) {
+           valarray<double> &x, 
+           valarray<double> const &b, 
+           unsigned const n, double const tol,
+           unsigned const max_iterations) {
+    //printf("Conjugate Gradient...\n");
     valarray<double> Ap(n), p(n), r(n);
     matrix_times_vector(A,x,Ap);
     r=b-Ap; 
     double r_r = inner(r,r);
     unsigned k = 0;
-    tol *= tol;
-    while(k < max_iterations && r_r > tol) {
+    double tol_squared = tol*tol;
+#ifdef EXAMINE_COST
+    double previousCost=compute_cost(A,b,x,n),cost;
+#endif
+    while(k < max_iterations && r_r > tol_squared) {
         k++;
         double r_r_new = r_r;
         if(k == 1)
             p = r;
         else {
             r_r_new = inner(r,r);
+            if(r_r_new<tol_squared) break;
             p = r + (r_r_new/r_r)*p;
         }
         matrix_times_vector(A, p, Ap);
         double alpha_k = r_r_new / inner(p, Ap);
         x += alpha_k*p;
+#ifdef EXAMINE_COST
+        cost=compute_cost(A,b,x,n);
+        printf("  CG[%d] %.15f %.15f\n",k,previousCost,cost);
+        previousCost=cost;
+#endif
         r -= alpha_k*Ap;
         r_r = r_r_new;
     }
+    //printf("  CG finished after %d iterations\n",k);
     //printf("njh: %d iters, Linfty = %g L2 = %g\n", k, 
     //std::max(-r.min(), r.max()), sqrt(r_r));
     // x is solution
 }
-/*
-  Local Variables:
-  mode:c++
-  c-file-style:"stroustrup"
-  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
-  indent-tabs-mode:nil
-  fill-column:99
-  End:
-*/
-// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=4:softtabstop=4