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| Rev | Author | Line No. | Line |
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| 4349 | Serge | 1 | |
| 2 | /* |
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| 3 | * ==================================================== |
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| 4 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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| 5 | * |
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| 6 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
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| 7 | * Permission to use, copy, modify, and distribute this |
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| 8 | * software is freely granted, provided that this notice |
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| 9 | * is preserved. |
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| 10 | * ==================================================== |
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| 11 | */ |
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| 12 | |||
| 13 | |||
| 14 | |||
| 15 | |||
| 16 | |||
| 17 | < |
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| 18 | |||
| 19 | |||
| 20 | tan |
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| 21 | INDEX |
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| 22 | tanf |
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| 23 | |||
| 24 | |||
| 25 | #include |
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| 26 | double tan(double <[x]>); |
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| 27 | float tanf(float <[x]>); |
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| 28 | |||
| 29 | |||
| 30 | #include |
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| 31 | double tan(<[x]>) |
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| 32 | double <[x]>; |
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| 33 | |||
| 34 | |||
| 35 | float <[x]>; |
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| 36 | |||
| 37 | |||
| 38 | |||
| 39 | < |
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| 40 | Angles are specified in radians. |
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| 41 | |||
| 42 | |||
| 43 | |||
| 44 | |||
| 45 | The tangent of <[x]> is returned. |
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| 46 | |||
| 47 | |||
| 48 | < |
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| 49 | */ |
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| 50 | |||
| 51 | |||
| 52 | * Return tangent function of x. |
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| 53 | * |
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| 54 | * kernel function: |
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| 55 | * __kernel_tan ... tangent function on [-pi/4,pi/4] |
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| 56 | * __ieee754_rem_pio2 ... argument reduction routine |
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| 57 | * |
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| 58 | * Method. |
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| 59 | * Let S,C and T denote the sin, cos and tan respectively on |
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| 60 | * [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2 |
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| 61 | * in [-pi/4 , +pi/4], and let n = k mod 4. |
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| 62 | * We have |
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| 63 | * |
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| 64 | * n sin(x) cos(x) tan(x) |
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| 65 | * ---------------------------------------------------------- |
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| 66 | * 0 S C T |
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| 67 | * 1 C -S -1/T |
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| 68 | * 2 -S -C T |
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| 69 | * 3 -C S -1/T |
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| 70 | * ---------------------------------------------------------- |
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| 71 | * |
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| 72 | * Special cases: |
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| 73 | * Let trig be any of sin, cos, or tan. |
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| 74 | * trig(+-INF) is NaN, with signals; |
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| 75 | * trig(NaN) is that NaN; |
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| 76 | * |
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| 77 | * Accuracy: |
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| 78 | * TRIG(x) returns trig(x) nearly rounded |
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| 79 | */ |
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| 80 | |||
| 81 | |||
| 82 | |||
| 83 | |||
| 84 | |||
| 85 | |||
| 86 | double tan(double x) |
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| 87 | #else |
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| 88 | double tan(x) |
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| 89 | double x; |
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| 90 | #endif |
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| 91 | { |
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| 92 | double y[2],z=0.0; |
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| 93 | __int32_t n,ix; |
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| 94 | |||
| 95 | |||
| 96 | GET_HIGH_WORD(ix,x); |
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| 97 | |||
| 98 | |||
| 99 | ix &= 0x7fffffff; |
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| 100 | if(ix <= 0x3fe921fb) return __kernel_tan(x,z,1); |
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| 101 | |||
| 102 | |||
| 103 | else if (ix>=0x7ff00000) return x-x; /* NaN */ |
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| 104 | |||
| 105 | |||
| 106 | else { |
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| 107 | n = __ieee754_rem_pio2(x,y); |
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| 108 | return __kernel_tan(y[0],y[1],1-((n&1)<<1)); /* 1 -- n even |
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| 109 | -1 -- n odd */ |
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| 110 | } |
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| 111 | } |
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| 112 | |||
| 113 | |||
| 114 |