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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 gcc Clojure C# Mono C++ g++ Dart Erlang HiPE F# Mono Fortran Intel Go Haskell GHC Java 7 Lisp SBCL OCaml Pascal Free Pascal Perl PHP Python 3 Racket Ruby 2.0 Ruby JRuby Scala x86 one core x64 quad-core x86 quad-core x64 one core

 performance measurements

Each table row shows performance measurements for this Java 7 program with a particular command-line input value N.

N	CPU secs	Elapsed secs	Memory KB	Code B	≈ CPU Load
500	0.30	0.25	240	514	16% 4% 96% 12%
3,000	5.16	5.10	14,704	514	1% 1% 1% 100%
5,500	16.90	16.85	15,236	514	1% 0% 1% 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

java version "1.7.0_11"
Java(TM) SE Runtime Environment (build 1.7.0_11-b21)
Java HotSpot(TM) Server VM (build 23.6-b04, mixed mode)

 spectral-norm Java 7 program source code

/* The Computer Language Benchmarks Game
   http://benchmarksgame.alioth.debian.org/
 
 contributed by Java novice Jarkko Miettinen
 modified ~3 lines of the original C#-version 
 by Isaac Gouy
 */
 
import java.text.DecimalFormat;
import java.text.NumberFormat; 

public class spectralnorm
{
   
   private static final NumberFormat formatter = new DecimalFormat("#.000000000");
   
   public static void main(String[] args) {
      int n = 100;
      if (args.length > 0) n = Integer.parseInt(args[0]);
      
      System.out.println(formatter.format(new spectralnorm().Approximate(n)));
   }
   
   private final double Approximate(int n) {
      // create unit vector
      double[] u = new double[n];
      for (int i=0; i<n; i++) u[i] =  1;
      
      // 20 steps of the power method
      double[] v = new double[n];
      for (int i=0; i<n; i++) v[i] = 0;
      
      for (int i=0; i<10; i++) {
         MultiplyAtAv(n,u,v);
         MultiplyAtAv(n,v,u);
      }
      
      // B=AtA         A multiplied by A transposed
      // v.Bv /(v.v)   eigenvalue of v
      double vBv = 0, vv = 0;
      for (int i=0; i<n; i++) {
         vBv += u[i]*v[i];
         vv  += v[i]*v[i];
      }
      
      return Math.sqrt(vBv/vv);
   }
   
   
   /* return element i,j of infinite matrix A */
   private final double A(int i, int j){
      return 1.0/((i+j)*(i+j+1)/2 +i+1);
   }
   
   /* multiply vector v by matrix A */
   private final void MultiplyAv(int n, double[] v, double[] Av){
      for (int i=0; i<n; i++){
         Av[i] = 0;
         for (int j=0; j<n; j++) Av[i] += A(i,j)*v[j];
      }
   }
   
   /* multiply vector v by matrix A transposed */
   private final void MultiplyAtv(int n, double[] v, double[] Atv){
      for (int i=0;i<n;i++){
         Atv[i] = 0;
         for (int j=0; j<n; j++) Atv[i] += A(j,i)*v[j];
      }
   }
   
   /* multiply vector v by matrix A and then by matrix A transposed */
   private final void MultiplyAtAv(int n, double[] v, double[] AtAv){
      double[] u = new double[n];
      MultiplyAv(n,v,u);
      MultiplyAtv(n,u,AtAv);
   }
}

 make, command-line, and program output logs

Mon, 21 Jan 2013 05:56:37 GMT

MAKE:
mv spectralnorm.java spectralnorm.java
mv: `spectralnorm.java' and `spectralnorm.java' are the same file
make: [spectralnorm.java_run] Error 1 (ignored)
/usr/local/src/jdk1.7.0_11/bin/javac spectralnorm.java
0.53s to complete and log all make actions

COMMAND LINE:
/usr/local/src/jdk1.7.0_11/bin/java  -server -XX:+TieredCompilation -XX:+AggressiveOpts spectralnorm 5500

PROGRAM OUTPUT:
1.274224153

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