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Diffstat (limited to '')
-rw-r--r-- | dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/shootout/spectral-norm.c | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/shootout/spectral-norm.c b/dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/shootout/spectral-norm.c new file mode 100644 index 0000000..9247543 --- /dev/null +++ b/dependencies/pkg/mod/golang.org/x/exp@v0.0.0-20220613132600-b0d781184e0d/shootout/spectral-norm.c @@ -0,0 +1,84 @@ +// +build ignore + +/* +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; +} |