LALInferenceDistanceMarg.c

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//
//  LALInferenceDistanceMarg.c
//
//
//  Created by John Veitch on 20/03/2018.
//
 
#include "LALInferenceDistanceMarg.h"
#include <math.h>
#include <gsl/gsl_integration.h>
 
 
struct integrand_args
{
    double A,B;
};
 
double dist_integral(double rho_opt, double rho_match, double dist_min, double dist_max)
{
    size_t limit=1000;
    double result,abserr;
    gsl_function F;
    gsl_integration_workspace *workspace = gsl_integration_workspace_alloc (limit);
 
    F.function = &dist_snr_pdf;
    struct integrand_args args = {.A=rho_opt, .B=rho_match};
    F.params = &args;
 
    gsl_integration_qag (&F, dist_min, dist_max, 0.1, 1e-6, limit, GSL_INTEG_GAUSS61, workspace, &result, &abserr);
    gsl_integration_workspace_free(workspace);
    return(result / (dist_max-dist_min));
}
 
 
double dist_snr_pdf(double dL, void *args)
{
    struct integrand_args *a = (struct integrand_args *)args;
    double result = exp(-a->A/dL/dL + a->B/dL)*dL*dL;
        return result;
}