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https://github.com/paboyle/Grid.git
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63 lines
1.7 KiB
C++
63 lines
1.7 KiB
C++
#include <Grid.h>
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using namespace std;
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using namespace Grid;
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using namespace Grid::QCD;
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int main (int argc, char ** argv)
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{
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Grid_init(&argc,&argv);
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std::cout << "Testing Remez"<<std::endl;
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double lo=0.01;
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double hi=1.0;
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int precision=64;
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int degree=10;
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AlgRemez remez(0.001,1.0,precision);
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////////////////////////////////////////
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// sqrt and inverse sqrt
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////////////////////////////////////////
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std::cout << "Generating degree "<<degree<<" for x^(1/2)"<<std::endl;
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remez.generateApprox(degree,1,2);
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MultiShiftFunction Sqrt(remez,1.0,false);
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MultiShiftFunction InvSqrt(remez,1.0,true);
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std::cout << "Generating degree "<<degree<<" for x^(1/4)"<<std::endl;
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remez.generateApprox(degree,1,4);
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MultiShiftFunction SqrtSqrt(remez,1.0,false);
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MultiShiftFunction InvSqrtSqrt(remez,1.0,true);
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ofstream gnuplot(std::string("Sqrt.gnu"),std::ios::out|std::ios::trunc);
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Sqrt.gnuplot(gnuplot);
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ofstream gnuplot_inv(std::string("InvSqrt.gnu"),std::ios::out|std::ios::trunc);
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InvSqrt.gnuplot(gnuplot);
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double x=0.6789;
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double sx=std::sqrt(x);
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double ssx=std::sqrt(sx);
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double isx=1.0/sx;
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double issx=1.0/ssx;
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double asx =Sqrt.approx(x);
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double assx =SqrtSqrt.approx(x);
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double aisx =InvSqrt.approx(x);
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double aissx=InvSqrtSqrt.approx(x);
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std::cout << "x^(1/2) : "<<sx<<" "<<asx<<std::endl;
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std::cout << "x^(1/4) : "<<ssx<<" "<<assx<<std::endl;
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std::cout << "x^(-1/2): "<<isx<<" "<<aisx<<std::endl;
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std::cout << "x^(-1/4): "<<issx<<" "<<aissx<<std::endl;
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assert(fabs(sx-asx)<1.0e-6);
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assert(fabs(ssx-assx)<1.0e-6);
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assert(fabs(isx-aisx)<1.0e-6);
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assert(fabs(issx-aissx)<1.0e-6);
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Grid_finalize();
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}
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