[444] | 1 | |
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| 2 | /* @(#)s_ldexp.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 | FUNCTION |
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| 16 | <<ldexp>>, <<ldexpf>>---load exponent |
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| 17 | |
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| 18 | INDEX |
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| 19 | ldexp |
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| 20 | INDEX |
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| 21 | ldexpf |
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| 22 | |
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| 23 | SYNOPSIS |
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| 24 | #include <math.h> |
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| 25 | double ldexp(double <[val]>, int <[exp]>); |
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| 26 | float ldexpf(float <[val]>, int <[exp]>); |
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| 27 | |
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| 28 | DESCRIPTION |
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| 29 | <<ldexp>> calculates the value |
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| 30 | @ifnottex |
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| 31 | <[val]> times 2 to the power <[exp]>. |
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| 32 | @end ifnottex |
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| 33 | @tex |
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| 34 | $val\times 2^{exp}$. |
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| 35 | @end tex |
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| 36 | <<ldexpf>> is identical, save that it takes and returns <<float>> |
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| 37 | rather than <<double>> values. |
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| 38 | |
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| 39 | RETURNS |
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| 40 | <<ldexp>> returns the calculated value. |
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| 41 | |
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| 42 | Underflow and overflow both set <<errno>> to <<ERANGE>>. |
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| 43 | On underflow, <<ldexp>> and <<ldexpf>> return 0.0. |
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| 44 | On overflow, <<ldexp>> returns plus or minus <<HUGE_VAL>>. |
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| 45 | |
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| 46 | PORTABILITY |
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| 47 | <<ldexp>> is ANSI. <<ldexpf>> is an extension. |
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| 48 | |
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| 49 | */ |
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| 50 | |
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| 51 | #include "fdlibm.h" |
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| 52 | #include <errno.h> |
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| 53 | |
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| 54 | #ifndef _DOUBLE_IS_32BITS |
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| 55 | |
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| 56 | #ifdef __STDC__ |
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| 57 | double ldexp(double value, int exp) |
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| 58 | #else |
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| 59 | double ldexp(value, exp) |
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| 60 | double value; int exp; |
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| 61 | #endif |
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| 62 | { |
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| 63 | if(!finite(value)||value==0.0) return value; |
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| 64 | value = scalbn(value,exp); |
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| 65 | if(!finite(value)||value==0.0) errno = ERANGE; |
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| 66 | return value; |
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| 67 | } |
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| 68 | |
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| 69 | #endif /* _DOUBLE_IS_32BITS */ |
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