/Proj4/adjlon.c

http://github.com/route-me/route-me · C · 18 lines · 15 code · 2 blank · 1 comment · 1 complexity · 692d74d9d370e691d60d6b89d58c441f MD5 · raw file 

    

  1. /* reduce argument to range +/- PI */
    2. 

  2. #ifndef lint
    3. 

  3. static const char SCCSID[]="@(#)adjlon.c	4.3	93/06/12	GIE	REL";
    4. 

  4. #endif
    5. 

  5. #include <math.h>
    6. 

  6. #include "projects.h"
    7. 

  7. 

  8. #define SPI     3.14159265359
    9. 

  9. #define TWOPI   6.2831853071795864769
    10. 

  10. #define ONEPI   3.14159265358979323846
    11. 

  11. 

  12. double adjlon (double lon) {
    13. 

  13.     if (fabs(lon) <= SPI) return( lon );
    14. 

  14.     lon += ONEPI;  /* adjust to 0..2pi rad */
    15. 

  15.     lon -= TWOPI * floor(lon / TWOPI); /* remove integral # of 'revolutions'*/
    16. 

  16.     lon -= ONEPI;  /* adjust back to -pi..pi rad */
    17. 

  17.     return( lon );
    18. 

  18. }
    19.