ReactOS 0.4.15-dev-7674-gc0b4db1
asin.c
Go to the documentation of this file.
1/*
2 * COPYRIGHT: See COPYING in the top level directory
3 * PROJECT: ReactOS CRT
4 * FILE: lib/sdk/crt/math/amd64/asin.c
5 * PURPOSE: Generic C implementation of arc sine
6 * PROGRAMMER: Timo Kreuzer (timo.kreuzer@reactos.org)
7 */
8
9#define PRECISION 9
10
11/*
12 * The arc sine can be approximated with the following row:
13 *
14 * asin(x) = a0*x + a1*x^3 + a2*x^5 + a3*x^7 + a4*x^9 + ...
15 *
16 * To reduce the number of multiplications the formula is transformed to
17 *
18 * asin(x) = x * (1 + x^2*(a1 + x^2*(a2 + x^2*(a3 + ...) ) ) )
19 *
20 * The coefficients are:
21 * a0 = 1
22 * a1 = (1/2*3)
23 * a2 = (3*1/4*2*5)
24 * a3 = (5*3*1/6*4*2*7)
25 * a4 = (7*5*3*1/8*6*4*2*9)
26 * a5 = (9*7*5*3*1/10*8*6*4*2*11)
27 * ...
28 */
29
30double
31asin(double x)
32{
33 double x2, result;
34
35 /* Check range */
36 if ((x > 1.) || (x < -1.)) return NaN;
37
38 /* Calculate the square of x */
39 x2 = (x * x);
40
41 /* Start with 0, compiler will optimize this away */
42 result = 0;
43
44 result += (15*13*11*9*7*5*3*1./(16*14*12*10*8*6*4*2*17));
45 result *= x2;
46
47 result += (13*11*9*7*5*3*1./(14*12*10*8*6*4*2*15));
48 result *= x2;
49
50 result += (11*9*7*5*3*1./(12*10*8*6*4*2*13));
51 result *= x2;
52
53 result += (9*7*5*3*1./(10*8*6*4*2*11));
54 result *= x2;
55
56 result += (7*5*3*1./(8*6*4*2*9));
57 result *= x2;
58
59 result += (5*3*1./(6*4*2*7));
60 result *= x2;
61
62 result += (3*1./(4*2*5));
63 result *= x2;
64
65 result += (1./(2*3));
66 result *= x2;
67
68 result += 1.;
69 result *= x;
70
71 return result;
72}
73
double asin(double x)
Definition: asin.c:31
GLint GLint GLint GLint GLint x
Definition: gl.h:1548
GLuint64EXT * result
Definition: glext.h:11304
_In_ CLIPOBJ _In_ BRUSHOBJ _In_ LONG _In_ LONG _In_ LONG x2
Definition: winddi.h:3710