/* -*- LPC -*- */
/*
* $Locker: $
* $Id: trig.c,v 1.1 1998/01/06 05:03:33 ceres Exp $
* $Log: trig.c,v $
* Revision 1.1 1998/01/06 05:03:33 ceres
* Initial revision
*
*/
/* this is [als]'s wonder trig object */
int *sintab, *pow;
create()
{
pow = ({ 296296, 308556, 321324, 334621, 348467, 362887, 377903,
393541, 409825, 426784, 444444, 462835, 481987, 501931,
522701, 544331, 566855, 590311, 614738, 640176, 666666,
694253, 722981, 752897, 784052, 816496, 850283, 885467,
922107, 960264, 1000000,
1041379, 1084471, 1129346, 1176079, 1224744, 1275424,
1328201, 1383161, 1440396, 1500000, 1562069, 1626707,
1694020, 1764118, 1837117, 1913136, 1992301, 2074742,
2160595, 2250000, 2343104, 2440061, 2541030, 2646177,
2755675, 2869705, 2988452, 3112114, 3240892, 3375000
});
sintab = ({
0, 17452, 34899, 52335, 69756, 87155, 104528, 121869, 139173, 156434,
173648, 190808, 207911, 224951, 241921, 258819, 275637, 292371,
309016, 325568, 342020, 358367, 374606, 390731, 406736, 422618,
438371, 453990, 469471, 484809, 500000, 515038, 529919, 544639,
559192, 573576, 587785, 601815, 615661, 629320, 642787, 656059,
669130, 681998, 694658, 707106, 719339, 731353, 743144, 754709,
766044, 777145, 788010, 798635, 809016, 819152, 829037, 838670,
848048, 857167, 866025, 874619, 882947, 891006, 898794, 906307,
913545, 920504, 927183, 933580, 939692, 945518, 951056, 956304,
961261, 965925, 970295, 974370, 978147, 981627, 984807, 987688,
990268, 992546, 994521, 996194, 997564, 998629, 999390, 999847, 1000000
});
}
int sin(int angle)
/* return sin(angle in degrees) * 1000000 */
{
/* for 'huge' angles this may be slow, but for the small angles we are expecting
it is fine */
while (angle < 0) angle += 360;
while (angle >= 360) angle -= 360;
if (angle >= 270) return -sintab[360 - angle];
if (angle >= 180) return -sintab[angle - 180];
if (angle >= 90) return sintab[180 - angle];
return sintab[angle];
}
int cos(int angle)
{
return sin(90 - angle);
}
int tan(int angle)
{
/* 1000 * 1e6 is the maximum ... so we have to divide the bottom by 1000 :(
losing accuracy along the way of course. */
return 1000 * sin(angle) / (sin(90 - angle) / 1000);
}
int pow1_5(int n)
{
if (n > 30) n = 30;
else if (n < -30) n = -30;
return pow[30-n];
}
