From 5ff4c17907d5b19510a62e08fd8d3b11e62b431d Mon Sep 17 00:00:00 2001
From: Ondřej Surý <ondrej@sury.org>
Date: Tue, 13 Sep 2011 13:13:40 +0200
Subject: Imported Upstream version 60

---
 test/bench/spectral-norm.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 test/bench/spectral-norm.c

(limited to 'test/bench/spectral-norm.c')

diff --git a/test/bench/spectral-norm.c b/test/bench/spectral-norm.c
new file mode 100644
index 000000000..832eb3d21
--- /dev/null
+++ b/test/bench/spectral-norm.c
@@ -0,0 +1,82 @@
+/*
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in the
+    documentation and/or other materials provided with the distribution.
+
+    * Neither the name of "The Computer Language Benchmarks Game" nor the
+    name of "The Computer Language Shootout Benchmarks" nor the names of
+    its contributors may be used to endorse or promote products derived
+    from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+*/
+
+/* -*- mode: c -*-
+ *
+ * The Great Computer Language Shootout
+ * http://shootout.alioth.debian.org/
+ *
+ * Contributed by Sebastien Loisel
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+
+double eval_A(int i, int j) { return 1.0/((i+j)*(i+j+1)/2+i+1); }
+
+void eval_A_times_u(int N, const double u[], double Au[])
+{
+  int i,j;
+  for(i=0;i<N;i++)
+    {
+      Au[i]=0;
+      for(j=0;j<N;j++) Au[i]+=eval_A(i,j)*u[j];
+    }
+}
+
+void eval_At_times_u(int N, const double u[], double Au[])
+{
+  int i,j;
+  for(i=0;i<N;i++)
+    {
+      Au[i]=0;
+      for(j=0;j<N;j++) Au[i]+=eval_A(j,i)*u[j];
+    }
+}
+
+void eval_AtA_times_u(int N, const double u[], double AtAu[])
+{ double v[N]; eval_A_times_u(N,u,v); eval_At_times_u(N,v,AtAu); }
+
+int main(int argc, char *argv[])
+{
+  int i;
+  int N = ((argc == 2) ? atoi(argv[1]) : 2000);
+  double u[N],v[N],vBv,vv;
+  for(i=0;i<N;i++) u[i]=1;
+  for(i=0;i<10;i++)
+    {
+      eval_AtA_times_u(N,u,v);
+      eval_AtA_times_u(N,v,u);
+    }
+  vBv=vv=0;
+  for(i=0;i<N;i++) { vBv+=u[i]*v[i]; vv+=v[i]*v[i]; }
+  printf("%0.9f\n",sqrt(vBv/vv));
+  return 0;
+}
-- 
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