Last change
on this file was
444,
checked in by satin@…, 6 years ago
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add newlib,libalmos-mkh, restructure shared_syscalls.h and mini-libc
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File size:
1.3 KB
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Rev | Line | |
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[444] | 1 | |
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| 2 | /* @(#)z_atan.c 1.0 98/08/13 */ |
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| 3 | |
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| 4 | /* |
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| 5 | FUNCTION |
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| 6 | <<atan>>, <<atanf>>---arc tangent |
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| 7 | |
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| 8 | INDEX |
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| 9 | atan |
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| 10 | INDEX |
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| 11 | atanf |
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| 12 | |
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| 13 | SYNOPSIS |
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| 14 | #include <math.h> |
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| 15 | double atan(double <[x]>); |
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| 16 | float atanf(float <[x]>); |
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| 17 | |
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| 18 | DESCRIPTION |
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| 19 | |
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| 20 | <<atan>> computes the inverse tangent (arc tangent) of the input value. |
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| 21 | |
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| 22 | <<atanf>> is identical to <<atan>>, save that it operates on <<floats>>. |
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| 23 | |
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| 24 | RETURNS |
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| 25 | @ifnottex |
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| 26 | <<atan>> returns a value in radians, in the range of -pi/2 to pi/2. |
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| 27 | @end ifnottex |
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| 28 | @tex |
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| 29 | <<atan>> returns a value in radians, in the range of $-\pi/2$ to $\pi/2$. |
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| 30 | @end tex |
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| 31 | |
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| 32 | PORTABILITY |
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| 33 | <<atan>> is ANSI C. <<atanf>> is an extension. |
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| 34 | |
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| 35 | */ |
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| 36 | |
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| 37 | /****************************************************************** |
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| 38 | * Arctangent |
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| 39 | * |
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| 40 | * Input: |
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| 41 | * x - floating point value |
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| 42 | * |
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| 43 | * Output: |
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| 44 | * arctan of x |
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| 45 | * |
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| 46 | * Description: |
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| 47 | * This routine returns the arctan of x. |
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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 "zmath.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 | double |
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| 57 | atan (double x) |
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| 58 | { |
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| 59 | switch (numtest (x)) |
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| 60 | { |
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| 61 | case NAN: |
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| 62 | errno = EDOM; |
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| 63 | return (x); |
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| 64 | case INF: |
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| 65 | /* this should check to see if neg NaN or pos NaN... */ |
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| 66 | return (__PI_OVER_TWO); |
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| 67 | case 0: |
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| 68 | return (0.0); |
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| 69 | default: |
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| 70 | return (atangent (x, 0, 0, 0)); |
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| 71 | } |
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| 72 | } |
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| 73 | |
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| 74 | #endif /* _DOUBLE_IS_32BITS */ |
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