/Proj4/pj_qsfn.c

 1/* determine small q */
 2#ifndef lint
 3static const char SCCSID[]="@(#)pj_qsfn.c	4.3	93/06/12	GIE	REL";
 4#endif
 5#include <math.h>
 6#include "projects.h"
 7
 8# define EPSILON 1.0e-7
 9	double
10pj_qsfn(double sinphi, double e, double one_es) {
11	double con;
12
13	if (e >= EPSILON) {
14		con = e * sinphi;
15		return (one_es * (sinphi / (1. - con * con) -
16		   (.5 / e) * log ((1. - con) / (1. + con))));
17	} else
18		return (sinphi + sinphi);
19}