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54aec05989
but non-identity matrix l1 0 0 0 .... 0 l2 0 0 .... 0 0 l3 0 ... . . . . . . . . . And apply the multishift CG to it. Sum the poles and residues. Insist that this be the same as the exactly taken square root where l1,l2,l3 >= 0.
30 lines
595 B
C++
30 lines
595 B
C++
#include <Grid.h>
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namespace Grid {
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double MultiShiftFunction::approx(double x)
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{
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double a = norm;
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for(int n=0;n<poles.size();n++){
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a = a + residues[n]/(x+poles[n]);
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}
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return a;
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}
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void MultiShiftFunction::gnuplot(std::ostream &out)
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{
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out<<"f(x) = "<<norm<<"";
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for(int n=0;n<poles.size();n++){
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out<<"+("<<residues[n]<<"/(x+"<<poles[n]<<"))";
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}
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out<<";"<<std::endl;
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}
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void MultiShiftFunction::csv(std::ostream &out)
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{
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for (double x=lo; x<hi; x*=1.05) {
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double f = approx(x);
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double r = sqrt(x);
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out<< x<<","<<r<<","<<f<<","<<r-f<<std::endl;
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}
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return;
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}
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}
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