fix incomplete gamma for negative x; tests

Former-commit-id: 688dc830c0b9396ceea7f503783f62d760ccf601
This commit is contained in:
Marek Nečada 2018-08-20 16:29:36 +03:00
parent f273a46a9a
commit 7093ff3add
4 changed files with 44 additions and 3 deletions

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@ -65,10 +65,11 @@ int cx_gamma_inc_series_e(double a, complex z, qpms_csf_result * result) {
// incomplete gamma for complex second argument // incomplete gamma for complex second argument
int complex_gamma_inc_e(double a, complex double x, qpms_csf_result *result) { int complex_gamma_inc_e(double a, complex double x, qpms_csf_result *result) {
if (0 == fabs(cimag(x)) && // x is real; just use the real fun if (creal(x) >= 0 &&
fabs(cimag(x)) < fabs(creal(x)) * COMPLEXPART_REL_ZERO_LIMIT) { (0 == fabs(cimag(x)) || // x is real positive; just use the real fun
fabs(cimag(x)) < fabs(creal(x)) * COMPLEXPART_REL_ZERO_LIMIT)) {
gsl_sf_result real_gamma_inc_result; gsl_sf_result real_gamma_inc_result;
int retval = gsl_sf_gamma_inc_e(a, x, &real_gamma_inc_result); int retval = gsl_sf_gamma_inc_e(a, creal(x), &real_gamma_inc_result);
result->val = real_gamma_inc_result.val; result->val = real_gamma_inc_result.val;
result->err = real_gamma_inc_result.err; result->err = real_gamma_inc_result.err;
return retval; return retval;

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@ -0,0 +1,12 @@
import random
import math
jmu = 2
mu = 5
for i in range(10000):
x = abs(random.expovariate(1/mu))
j = math.floor(abs(random.expovariate(1/jmu)))
print(j, x)

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@ -0,0 +1,28 @@
#include <gsl/gsl_sf_gamma.h>
#include <gsl/gsl_sf_result.h>
#include <qpms/ewald.h>
#include <stdio.h>
#include <math.h>
#include <complex.h>
//#include <gsl/gsl_integration.h>
#include <gsl/gsl_errno.h>
int main(int argc, char **argv) {
gsl_error_handler_t * old_handler=gsl_set_error_handler_off();
int j;
double x;
while (scanf("%d %lf", &j, &x) == 2) {
printf("%d %.16g", j, x);
qpms_csf_result res;
complex double argfac = 1;
for (int i = 0; i < 4; ++i, argfac *= I) {
int retval = complex_gamma_inc_e(0.5-j, argfac * x, &res);
printf(" | %.16g+%.16gj %.4g %d", creal(res.val), cimag(res.val), res.err, retval);
}
putchar('\n');
}
return 0;
}