ReactOS  0.4.15-dev-1619-g69dffed
sin.c
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1 /*
2  * COPYRIGHT: See COPYING in the top level directory
3  * PROJECT: ReactOS CRT
4  * FILE: lib/sdk/crt/math/sin.c
5  * PURPOSE: Generic C Implementation of sin
6  * PROGRAMMER: Timo Kreuzer (timo.kreuzer@reactos.org)
7  */
8
9 #ifdef _MSC_VER
10 #pragma warning(suppress:4164) /* intrinsic not declared */
11 #pragma function(sin)
12 #endif /* _MSC_VER */
13
14 #define PRECISION 9
15 #define M_PI 3.141592653589793238462643
16
17 static double sin_off_tbl[] = {0.0, -M_PI/2., 0, -M_PI/2.};
18 static double sin_sign_tbl[] = {1,-1,-1,1};
19
20 double
21 sin(double x)
22 {
24  double x2, result;
25
26  /* Calculate the quadrant */
27  quadrant = (int)(x * (2./M_PI));
28
29  /* Get offset inside quadrant */
30  x = x - quadrant * (M_PI/2.);
31
32  /* Normalize quadrant to [0..3] */
34
35  /* Fixup value for the generic function */
37
38  /* Calculate the negative of the square of x */
39  x2 = - (x * x);
40
41  /* This is an unrolled taylor series using <PRECISION> iterations
42  * Example with 4 iterations:
43  * result = 1 - x^2/2! + x^4/4! - x^6/6! + x^8/8!
44  * To save multiplications and to keep the precision high, it's performed
45  * like this:
46  * result = 1 - x^2 * (1/2! - x^2 * (1/4! - x^2 * (1/6! - x^2 * (1/8!))))
47  */
48
50  result = 0;
51
52 #if (PRECISION >= 10)
53  result += 1./(1.*2*3*4*5*6*7*8*9*10*11*12*13*14*15*16*17*18*19*20);
54  result *= x2;
55 #endif
56 #if (PRECISION >= 9)
57  result += 1./(1.*2*3*4*5*6*7*8*9*10*11*12*13*14*15*16*17*18);
58  result *= x2;
59 #endif
60 #if (PRECISION >= 8)
61  result += 1./(1.*2*3*4*5*6*7*8*9*10*11*12*13*14*15*16);
62  result *= x2;
63 #endif
64 #if (PRECISION >= 7)
65  result += 1./(1.*2*3*4*5*6*7*8*9*10*11*12*13*14);
66  result *= x2;
67 #endif
68 #if (PRECISION >= 6)
69  result += 1./(1.*2*3*4*5*6*7*8*9*10*11*12);
70  result *= x2;
71 #endif
72 #if (PRECISION >= 5)
73  result += 1./(1.*2*3*4*5*6*7*8*9*10);
74  result *= x2;
75 #endif
76  result += 1./(1.*2*3*4*5*6*7*8);
77  result *= x2;
78
79  result += 1./(1.*2*3*4*5*6);
80  result *= x2;
81
82  result += 1./(1.*2*3*4);
83  result *= x2;
84
85  result += 1./(1.*2);
86  result *= x2;
87
88  result += 1;
89
90  /* Apply correct sign */
92
93  return result;
94 }
GLuint64EXT * result
Definition: glext.h:11304
static double sin_off_tbl[]
Definition: sin.c:17
GLint GLint GLint GLint GLint x
Definition: gl.h:1548
static double sin_sign_tbl[]
Definition: sin.c:18
#define M_PI
Definition: sin.c:15
double sin(double x)
Definition: sin.c:21
_In_ CLIPOBJ _In_ BRUSHOBJ _In_ LONG _In_ LONG _In_ LONG x2
Definition: winddi.h:3706