1 files changed, 154 insertions, 0 deletions
diff --git a/src/2geom/numeric/matrix.cpp b/src/2geom/numeric/matrix.cpp
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+/*
+ * Matrix, MatrixView, ConstMatrixView classes wrap the gsl matrix routines;
+ * "views" mimic the semantic of C++ references: any operation performed
+ * on a "view" is actually performed on the "viewed object"
+ *
+ * Authors:
+ *      Marco Cecchetti <mrcekets at gmail.com>
+ *
+ * Copyright 2008  authors
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it either under the terms of the GNU Lesser General Public
+ * License version 2.1 as published by the Free Software Foundation
+ * (the "LGPL") or, at your option, under the terms of the Mozilla
+ * Public License Version 1.1 (the "MPL"). If you do not alter this
+ * notice, a recipient may use your version of this file under either
+ * the MPL or the LGPL.
+ *
+ * You should have received a copy of the LGPL along with this library
+ * in the file COPYING-LGPL-2.1; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ * You should have received a copy of the MPL along with this library
+ * in the file COPYING-MPL-1.1
+ *
+ * The contents of this file are subject to the Mozilla Public License
+ * Version 1.1 (the "License"); you may not use this file except in
+ * compliance with the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
+ * OF ANY KIND, either express or implied. See the LGPL or the MPL for
+ * the specific language governing rights and limitations.
+ */
+
+
+#include <2geom/numeric/matrix.h>
+#include <2geom/numeric/vector.h>
+
+
+namespace Geom { namespace NL {
+
+Vector operator*( detail::BaseMatrixImpl const& A,
+                  detail::BaseVectorImpl const& v )
+{
+    assert(A.columns() == v.size());
+
+    Vector result(A.rows(), 0.0);
+    for (size_t i = 0; i < A.rows(); ++i)
+        for (size_t j = 0; j < A.columns(); ++j)
+            result[i] += A(i,j) * v[j];
+
+    return result;
+}
+
+Matrix operator*( detail::BaseMatrixImpl const& A,
+                  detail::BaseMatrixImpl const& B )
+{
+    assert(A.columns() == B.rows());
+
+    Matrix C(A.rows(), B.columns(), 0.0);
+    for (size_t i = 0; i < C.rows(); ++i)
+        for (size_t j = 0; j < C.columns(); ++j)
+            for (size_t k = 0; k < A.columns(); ++k)
+                C(i,j) += A(i,k) * B(k, j);
+
+    return C;
+}
+
+Matrix pseudo_inverse(detail::BaseMatrixImpl const& A)
+{
+
+    Matrix U(A);
+    Matrix V(A.columns(), A.columns());
+    Vector s(A.columns());
+    gsl_vector* work = gsl_vector_alloc(A.columns());
+
+    gsl_linalg_SV_decomp( U.get_gsl_matrix(),
+                          V.get_gsl_matrix(),
+                          s.get_gsl_vector(),
+                          work );
+
+    Matrix P(A.columns(), A.rows(), 0.0);
+
+    int sz = s.size();
+    while ( sz-- > 0 && s[sz] == 0 ) {}
+    ++sz;
+    if (sz == 0) return P;
+    VectorView sv(s, sz);
+
+    for (size_t i = 0; i < sv.size(); ++i)
+    {
+        VectorView v = V.column_view(i);
+        v.scale(1/sv[i]);
+        for (size_t h = 0; h < P.rows(); ++h)
+            for (size_t k = 0; k < P.columns(); ++k)
+                P(h,k) += V(h,i) * U(k,i);
+    }
+
+    return P;
+}
+
+
+double trace (detail::BaseMatrixImpl const& A)
+{
+    if (A.rows() != A.columns())
+    {
+        THROW_RANGEERROR ("NL::Matrix: computing trace: "
+                          "rows() != columns()");
+    }
+    double t = 0;
+    for (size_t i = 0; i < A.rows(); ++i)
+    {
+        t += A(i,i);
+    }
+    return t;
+}
+
+
+double det (detail::BaseMatrixImpl const& A)
+{
+    if (A.rows() != A.columns())
+    {
+        THROW_RANGEERROR ("NL::Matrix: computing determinant: "
+                          "rows() != columns()");
+    }
+
+    Matrix LU(A);
+    int s;
+    gsl_permutation * p = gsl_permutation_alloc(LU.rows());
+    gsl_linalg_LU_decomp (LU.get_gsl_matrix(), p, &s);
+
+    double t = 1;
+    for (size_t i = 0; i < LU.rows(); ++i)
+    {
+        t *= LU(i,i);
+    }
+
+    gsl_permutation_free(p);
+    return t;
+}
+
+
+} }  // end namespaces
+
+/*
+  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=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :