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- /*
- * (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
- * See the copyright notice in the ACK home directory, in the file "Copyright".
- *
- * Author: Ceriel J.H. Jacobs
- */
- /* $Id$ */
- #include <math.h>
- #include <errno.h>
- #include "localmath.h"
- static double
- asin_acos(double x, int cosfl)
- {
- int negative = x < 0;
- int i;
- double g;
- static double p[] = {
- -0.27368494524164255994e+2,
- 0.57208227877891731407e+2,
- -0.39688862997540877339e+2,
- 0.10152522233806463645e+2,
- -0.69674573447350646411e+0
- };
- static double q[] = {
- -0.16421096714498560795e+3,
- 0.41714430248260412556e+3,
- -0.38186303361750149284e+3,
- 0.15095270841030604719e+3,
- -0.23823859153670238830e+2,
- 1.0
- };
- if (__IsNan(x)) {
- errno = EDOM;
- return x;
- }
- if (negative) {
- x = -x;
- }
- if (x > 0.5) {
- i = 1;
- if (x > 1) {
- errno = EDOM;
- return 0;
- }
- g = 0.5 - 0.5 * x;
- x = - sqrt(g);
- x += x;
- }
- else {
- /* ??? avoid underflow ??? */
- i = 0;
- g = x * x;
- }
- x += x * g * POLYNOM4(g, p) / POLYNOM5(g, q);
- if (cosfl) {
- if (! negative) x = -x;
- }
- if ((cosfl == 0) == (i == 1)) {
- x = (x + M_PI_4) + M_PI_4;
- }
- else if (cosfl && negative && i == 1) {
- x = (x + M_PI_2) + M_PI_2;
- }
- if (! cosfl && negative) x = -x;
- return x;
- }
- double
- asin(double x)
- {
- return asin_acos(x, 0);
- }
- double
- acos(double x)
- {
- return asin_acos(x, 1);
- }
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