| 9 |
|
* |
| 10 |
|
* No interpolation in this version. |
| 11 |
|
* |
| 12 |
< |
* External symbols declared in standard.h |
| 12 |
> |
* External symbols declared in rtmath.h |
| 13 |
|
*/ |
| 14 |
|
|
| 15 |
|
#include "copyright.h" |
| 19 |
|
#include "rtmath.h" |
| 20 |
|
|
| 21 |
|
#ifndef NCOSENTRY |
| 22 |
< |
#define NCOSENTRY 256 |
| 22 |
> |
#define NCOSENTRY 1024 |
| 23 |
|
#endif |
| 24 |
|
|
| 25 |
– |
#ifdef M_PI |
| 26 |
– |
#define PI ((double)M_PI) |
| 27 |
– |
#else |
| 28 |
– |
#define PI 3.14159265358979323846 |
| 29 |
– |
#endif |
| 25 |
|
|
| 31 |
– |
|
| 26 |
|
double |
| 27 |
< |
tcos(x) /* approximate cosine */ |
| 34 |
< |
register double x; |
| 27 |
> |
tcos(double x) /* approximate cosine */ |
| 28 |
|
{ |
| 29 |
|
static double costab[NCOSENTRY+1]; |
| 30 |
|
register int i; |
| 36 |
|
if (x < 0.) |
| 37 |
|
x = -x; |
| 38 |
|
i = (NCOSENTRY*2./PI) * x + 0.5; |
| 39 |
< |
if (i >= 4*NCOSENTRY) |
| 40 |
< |
i %= 4*NCOSENTRY; |
| 39 |
> |
while (i >= 4*NCOSENTRY) |
| 40 |
> |
i -= 4*NCOSENTRY; |
| 41 |
|
switch (i / NCOSENTRY) { |
| 42 |
|
case 0: |
| 43 |
|
return(costab[i]); |
| 49 |
|
return(costab[(4*NCOSENTRY)-i]); |
| 50 |
|
} |
| 51 |
|
return(0.); /* should never be reached */ |
| 52 |
+ |
} |
| 53 |
+ |
|
| 54 |
+ |
|
| 55 |
+ |
/* Fast arctangent approximation due to Rajan et al. 2006 */ |
| 56 |
+ |
double |
| 57 |
+ |
aatan2(double y, double x) |
| 58 |
+ |
{ |
| 59 |
+ |
double ratio, aratio, val; |
| 60 |
+ |
|
| 61 |
+ |
if (x == 0) |
| 62 |
+ |
return (y > 0) ? PI/2. : 3./2.*PI; |
| 63 |
+ |
|
| 64 |
+ |
aratio = (ratio = y/x) >= 0 ? ratio : -ratio; |
| 65 |
+ |
|
| 66 |
+ |
if (aratio > 1.01) |
| 67 |
+ |
return PI/2. - aatan2(x, y); |
| 68 |
+ |
|
| 69 |
+ |
val = PI/4.*ratio - ratio*(aratio - 1.)*(0.2447 + 0.0663*aratio); |
| 70 |
+ |
|
| 71 |
+ |
return val + PI*(x < 0); |
| 72 |
|
} |
