diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/adjlon.c | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/src/adjlon.c b/src/adjlon.c index 3de12a16..04f04400 100644 --- a/src/adjlon.c +++ b/src/adjlon.c @@ -3,14 +3,15 @@ static const char SCCSID[]="@(#)adjlon.c 4.3 93/06/12 GIE REL"; #endif #include <math.h> -/* note: PI adjusted high -** approx. true val: 3.14159265358979323844 -*/ -#define SPI 3.14159265359 -#define TWOPI 6.2831853071795864769 - double -adjlon (double lon) { - while ( fabs(lon) > SPI ) - lon += lon < 0. ? TWOPI : -TWOPI; - return( lon ); + +#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 ); } |