int work(int y1,int z1, double m1,
int y2,int z2, double m2,
int y3,int z3, double m3,
int y4,int z4, double m4,
int order,
double lambda_low, double lambda_high,
int precision,
char *tag1, char *tag2 ){
// The error from the approximation (the relative error is minimised
// - if another error minimisation is requried, then line 398 in
// alg_remez.C is where to change it)
double error;
double *res = new double[order];
double *pole = new double[order];
// The partial fraction expansion takes the form
// r(x) = norm + sum_{k=1}^{n} res[k] / (x + pole[k])
double norm;
double bulk = exp(0.5*(log(lambda_low)+log(lambda_high)));
// Instantiate the Remez class,
AlgRemez remez(lambda_low,lambda_high,precision);
// Generate the required approximation
fprintf(stderr,
"Generating a (%d,%d) rational function using %d digit precision.\n",
order,order,precision);
error = remez.generateApprox(order,order,y1,z1,m1,y2,z2,m2,
y3,z3,m3,y4,z4,m4);
// Find the partial fraction expansion of the approximation
// to the function x^{y/z} (this only works currently for
// the special case that n = d)
remez.getPFE(res,pole,&norm);
print_check_ratfunc(y1,y2,y3,y4,z1,z2,z3,z4,m1,m2,m3,m4,
lambda_low,order,norm,res,pole,tag1);
// Find pfe of the inverse function
remez.getIPFE(res,pole,&norm);
print_check_ratfunc(-y1,-y2,-y3,-y4,z1,z2,z3,z4,m1,m2,m3,m4,
lambda_low,order,norm,res,pole,tag2);
FILE *error_file = fopen("error.dat", "w");
for (double x=lambda_low; x<lambda_high; x*=1.01) {
double f = remez.evaluateFunc(x);
double r = remez.evaluateApprox(x);
fprintf(error_file,"%e %e\n", x, (r - f)/f);
}
fclose(error_file);
delete res;
delete pole;
}
// -----------------------------------------------------------------
int work(int Nroot, int order, double lambda_low, double lambda_high,
int precision, char *tag1, char *tag2) {
int Nroot4 = 4 * Nroot;
double *res = new double[order];
double *pole = new double[order];
double error; // The error from the approximation
// The relative error is minimised
// If another error minimisation is required,
// change line 398 in alg_remez.C
// The partial fraction expansion takes the form
// r(x) = norm + sum_{k=1}^{n} res[k] / (x + pole[k])
double norm;
double bulk = exp(0.5 * (log(lambda_low) + log(lambda_high)));
// Instantiate the Remez class
AlgRemez remez(lambda_low, lambda_high, precision);
// Generate the required approximation
fprintf(stderr, "Generating a (%d,%d) rational function ", order, order);
fprintf(stderr, "using %d digit precision\n", precision);
error = remez.generateApprox(order, order, 1, Nroot4, 0.0, 0, -1, -1.0,
0, -1, -1.0, 0, -1, -1.0);
// Find the partial fraction approximation to the function x^{y / z}
// This only works currently for the special case that n = d
remez.getPFE(res, pole, &norm);
print_check_ratfunc(1, Nroot4, lambda_low, order, norm, res, pole, tag1);
// Find pfe of the inverse function
remez.getIPFE(res, pole, &norm);
print_check_ratfunc(-1, Nroot4, lambda_low, order, norm, res, pole, tag2);
FILE *error_file = fopen("error.dat", "w");
double x, f, r;
for (x = lambda_low; x < lambda_high; x *= 1.01) {
f = remez.evaluateFunc(x);
r = remez.evaluateApprox(x);
fprintf(error_file, "%e %e\n", x, (r - f) / f);
}
fclose(error_file);
delete res;
delete pole;
}
