LRnexp.c

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/*
 * Copyright    2019    R.K. Owen, Ph.D.
 * License      see lgpl.md (Gnu Lesser General Public License)
 */
#ifdef __cplusplus
extern "C" {
#endif

#include <math.h>
#include "libran.h"

/* double */
double LRd_nexp_RAN(LR_obj *o) {
        double u, zero = 0.0, one = 1.0;

        do {
                u = o->ud(o);
        } while (u == zero);

        return - o->m.d*log(u);
}

double LRd_nexp_PDF(LR_obj *o, double x) {
        double zero = 0.0, one = 1.0;
        if (isnan(o->s.d))
                o->s.d = one/o->m.d;

        if (x < zero)   return zero;

        return o->s.d * exp(- o->s.d * x);
}

double LRd_nexp_CDF(LR_obj *o, double x) {
        double zero = 0.0, one = 1.0;
        if (isnan(o->s.d))
                o->s.d = one/o->m.d;

        if (x < zero)   return zero;

        return one - exp(- o->s.d * x);
}

/* float */
float LRf_nexp_RAN(LR_obj *o) {
        float u, zero = 0.0, one = 1.0;

        do {
                u = o->uf(o);
        } while (u == zero);

        return - o->m.f*log(u);
}

float LRf_nexp_PDF(LR_obj *o, float x) {
        float zero = 0.0, one = 1.0;
        if (isnan(o->s.f))
                o->s.f = one/o->m.f;

        if (x < zero)   return zero;

        return o->s.f * expf(- o->s.f * x);
}

float LRf_nexp_CDF(LR_obj *o, float x) {
        float zero = 0.0, one = 1.0;
        if (isnan(o->s.f))
                o->s.f = one/o->m.f;

        if (x < zero)   return zero;

        return one - expf(- o->s.f * x);
}

#ifdef __cplusplus
}
#endif