| gvSIG desktop 1

/* reduce argument to range +/- PI */

#ifndef lint

static const char SCCSID[]="@(#)adjlon.c        4.3        93/06/12        GIE        REL";

#endif

#include <math.h>

#include <projects.h>

#define SPI     3.14159265359

#define TWOPI   6.2831853071795864769

#define ONEPI   3.14159265358979323846

double adjlon (double lon) {

    if (fabs(lon) <= SPI) return( lon );

    lon += ONEPI;  /* adjust to 0..2pi rad */

    lon -= TWOPI * floor(lon / TWOPI); /* remove integral # of 'revolutions'*/

    lon -= ONEPI;  /* adjust back to -pi..pi rad */

    return( lon );

}