1 | |
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2 | /* @(#)w_atan2.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 | <<atan2>>, <<atan2f>>---arc tangent of y/x |
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18 | |
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19 | INDEX |
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20 | atan2 |
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21 | INDEX |
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22 | atan2f |
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23 | |
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24 | SYNOPSIS |
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25 | #include <math.h> |
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26 | double atan2(double <[y]>,double <[x]>); |
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27 | float atan2f(float <[y]>,float <[x]>); |
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28 | |
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29 | DESCRIPTION |
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30 | |
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31 | <<atan2>> computes the inverse tangent (arc tangent) of <[y]>/<[x]>. |
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32 | <<atan2>> produces the correct result even for angles near |
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33 | @ifnottex |
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34 | pi/2 or -pi/2 |
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35 | @end ifnottex |
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36 | @tex |
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37 | $\pi/2$ or $-\pi/2$ |
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38 | @end tex |
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39 | (that is, when <[x]> is near 0). |
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40 | |
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41 | <<atan2f>> is identical to <<atan2>>, save that it takes and returns |
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42 | <<float>>. |
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43 | |
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44 | RETURNS |
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45 | <<atan2>> and <<atan2f>> return a value in radians, in the range of |
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46 | @ifnottex |
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47 | -pi to pi. |
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48 | @end ifnottex |
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49 | @tex |
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50 | $-\pi$ to $\pi$. |
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51 | @end tex |
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52 | |
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53 | You can modify error handling for these functions using <<matherr>>. |
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54 | |
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55 | PORTABILITY |
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56 | <<atan2>> is ANSI C. <<atan2f>> is an extension. |
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57 | |
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58 | |
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59 | */ |
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60 | |
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61 | /* |
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62 | * wrapper atan2(y,x) |
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63 | */ |
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64 | |
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65 | #include "fdlibm.h" |
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66 | #include <errno.h> |
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67 | |
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68 | #ifndef _DOUBLE_IS_32BITS |
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69 | |
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70 | #ifdef __STDC__ |
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71 | double atan2(double y, double x) /* wrapper atan2 */ |
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72 | #else |
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73 | double atan2(y,x) /* wrapper atan2 */ |
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74 | double y,x; |
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75 | #endif |
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76 | { |
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77 | return __ieee754_atan2(y,x); |
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78 | } |
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79 | |
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80 | #endif /* defined(_DOUBLE_IS_32BITS) */ |
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