1 | |
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2 | /* @(#)w_cosh.c 5.1 93/09/24 */ |
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3 | /* |
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4 | * ==================================================== |
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5 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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6 | * |
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7 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
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8 | * Permission to use, copy, modify, and distribute this |
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9 | * software is freely granted, provided that this notice |
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10 | * is preserved. |
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11 | * ==================================================== |
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12 | */ |
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13 | |
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14 | /* |
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15 | |
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16 | FUNCTION |
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17 | <<cosh>>, <<coshf>>---hyperbolic cosine |
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18 | |
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19 | SYNOPSIS |
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20 | #include <math.h> |
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21 | double cosh(double <[x]>); |
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22 | float coshf(float <[x]>); |
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23 | |
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24 | DESCRIPTION |
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25 | |
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26 | <<cosh>> computes the hyperbolic cosine of the argument <[x]>. |
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27 | <<cosh(<[x]>)>> is defined as |
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28 | @ifnottex |
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29 | . (exp(x) + exp(-x))/2 |
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30 | @end ifnottex |
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31 | @tex |
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32 | $${(e^x + e^{-x})} \over 2$$ |
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33 | @end tex |
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34 | |
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35 | Angles are specified in radians. |
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36 | |
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37 | <<coshf>> is identical, save that it takes and returns <<float>>. |
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38 | |
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39 | RETURNS |
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40 | The computed value is returned. When the correct value would create |
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41 | an overflow, <<cosh>> returns the value <<HUGE_VAL>> with the |
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42 | appropriate sign, and the global value <<errno>> is set to <<ERANGE>>. |
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43 | |
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44 | You can modify error handling for these functions using the |
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45 | function <<matherr>>. |
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46 | |
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47 | PORTABILITY |
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48 | <<cosh>> is ANSI. |
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49 | <<coshf>> is an extension. |
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50 | |
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51 | QUICKREF |
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52 | cosh ansi pure |
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53 | coshf - pure |
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54 | */ |
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55 | |
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56 | /* |
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57 | * wrapper cosh(x) |
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58 | */ |
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59 | |
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60 | #include "fdlibm.h" |
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61 | #include <errno.h> |
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62 | |
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63 | #ifndef _DOUBLE_IS_32BITS |
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64 | |
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65 | #ifdef __STDC__ |
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66 | double cosh(double x) /* wrapper cosh */ |
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67 | #else |
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68 | double cosh(x) /* wrapper cosh */ |
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69 | double x; |
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70 | #endif |
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71 | { |
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72 | #ifdef _IEEE_LIBM |
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73 | return __ieee754_cosh(x); |
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74 | #else |
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75 | double z; |
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76 | struct exception exc; |
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77 | z = __ieee754_cosh(x); |
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78 | if(_LIB_VERSION == _IEEE_ || isnan(x)) return z; |
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79 | if(fabs(x)>7.10475860073943863426e+02) { |
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80 | /* cosh(finite) overflow */ |
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81 | #ifndef HUGE_VAL |
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82 | #define HUGE_VAL inf |
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83 | double inf = 0.0; |
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84 | |
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85 | SET_HIGH_WORD(inf,0x7ff00000); /* set inf to infinite */ |
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86 | #endif |
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87 | exc.type = OVERFLOW; |
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88 | exc.name = "cosh"; |
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89 | exc.err = 0; |
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90 | exc.arg1 = exc.arg2 = x; |
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91 | if (_LIB_VERSION == _SVID_) |
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92 | exc.retval = HUGE; |
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93 | else |
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94 | exc.retval = HUGE_VAL; |
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95 | if (_LIB_VERSION == _POSIX_) |
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96 | errno = ERANGE; |
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97 | else if (!matherr(&exc)) { |
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98 | errno = ERANGE; |
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99 | } |
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100 | if (exc.err != 0) |
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101 | errno = exc.err; |
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102 | return exc.retval; |
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103 | } else |
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104 | return z; |
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105 | #endif |
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106 | } |
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107 | |
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108 | #endif /* defined(_DOUBLE_IS_32BITS) */ |
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