Ubuntu : Intel® Q6600® one core
Computer Language Benchmarks Game      [[ Play ]]

- all benchmarks - n-body fannkuch-redux meteor-contest fasta fasta-redux spectral-norm reverse-complement mandelbrot k-nucleotide regex-dna pidigits chameneos-redux thread-ring binary-trees-redux binary-trees - all languages - Ada 2005 GNAT ATS C CINT C gcc Clojure C# Mono C++ g++ Dart Erlang HiPE F# Mono Fortran Intel Go Haskell GHC Java 7 JavaScript V8 Lisp SBCL Lua OCaml Pascal Free Pascal Perl PHP Python 3 Racket Ruby 2.0 Ruby JRuby Scala Smalltalk VisualWorks x86 one core x64 quad-core x86 quad-core x64 one core

 performance measurements

Each table row shows performance measurements for this C++ g++ program with a particular command-line input value N.

N	CPU secs	Elapsed secs	Memory KB	Code B	≈ CPU Load
500	0.24	0.25	264	452	0% 0% 4% 100%
3,000	8.48	8.48	872	452	0% 1% 1% 100%
5,500	28.47	28.48	872	452	0% 0% 0% 100%

Read the ↓ make, command line, and program output logs to see how this program was run.

Read spectral-norm benchmark to see what this program should do.

 notes

gcc (Ubuntu/Linaro 4.7.3-1ubuntu1) 4.7.3

 spectral-norm C++ g++ program source code

// The Computer Language Benchmarks Game
// http://benchmarksgame.alioth.debian.org/
//
// Original C contributed by Sebastien Loisel
// Conversion to C++ by Jon Harrop
// Compile: g++ -O3 -o spectralnorm spectralnorm.cpp


#include <stdio.h>
#include <stdlib.h>
#include <cmath>
#include <vector>
#include <iostream>
#include <iomanip>

using namespace std;

double eval_A(int i, int j) { return 1.0 / ((i+j)*(i+j+1)/2 + i + 1); }

void eval_A_times_u(const vector<double> &u, vector<double> &Au)
{
  for(int i=0; i<u.size(); i++)
    for(int j=0; j<u.size(); j++) Au[i] += eval_A(i,j) * u[j];
}

void eval_At_times_u(const vector<double> &u, vector<double> &Au)
{
  for(int i=0; i<u.size(); i++)
    for(int j=0; j<u.size(); j++) Au[i] += eval_A(j,i) * u[j];
}

void eval_AtA_times_u(const vector<double> &u, vector<double> &AtAu)
{ vector<double> v(u.size()); eval_A_times_u(u, v); eval_At_times_u(v, AtAu); }

int main(int argc, char *argv[])
{
  int N = ((argc == 2) ? atoi(argv[1]) : 2000);
  vector<double> u(N), v(N);

  fill(u.begin(), u.end(), 1);

  for(int i=0; i<10; i++) {
    eval_AtA_times_u(u, v);
    fill(u.begin(), u.end(), 0);
    eval_AtA_times_u(v, u);
  }

  double vBv=0, vv=0;
  for(int i=0; i<N; i++) { vBv += u[i]*v[i]; vv += v[i]*v[i]; }

  cout << setprecision(10) << sqrt(vBv/vv) << endl;

  return 0;
}

 make, command-line, and program output logs

Tue, 30 Apr 2013 05:50:38 GMT

MAKE:
/usr/bin/g++ -c -pipe -O3 -fomit-frame-pointer -march=native -mfpmath=sse -msse2 -fopenmp -O0 spectralnorm.c++ -o spectralnorm.c++.o &&  \
        /usr/bin/g++ spectralnorm.c++.o -o spectralnorm.gpp_run -fopenmp 
rm spectralnorm.c++
0.38s to complete and log all make actions

COMMAND LINE:
./spectralnorm.gpp_run 5500

PROGRAM OUTPUT:
1.274224153

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