1 | /* origin: FreeBSD /usr/src/lib/msun/src/e_atan2l.c */
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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 SunSoft, 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 | */
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13 | /*
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14 | * See comments in atan2.c.
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15 | * Converted to long double by David Schultz <das@FreeBSD.ORG>.
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16 | */
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17 |
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18 | #include "libm.h"
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19 |
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20 | #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
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21 | long double atan2l(long double y, long double x)
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22 | {
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23 | return atan2(y, x);
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24 | }
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25 | #elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
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26 | #include "__invtrigl.h"
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27 |
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28 | long double atan2l(long double y, long double x)
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29 | {
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30 | union ldshape ux, uy;
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31 | long double z;
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32 | int m, ex, ey;
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33 |
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34 | if (isnan(x) || isnan(y))
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35 | return x+y;
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36 | if (x == 1)
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37 | return atanl(y);
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38 | ux.f = x;
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39 | uy.f = y;
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40 | ex = ux.i.se & 0x7fff;
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41 | ey = uy.i.se & 0x7fff;
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42 | m = 2*(ux.i.se>>15) | uy.i.se>>15;
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43 | if (y == 0) {
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44 | switch(m) {
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45 | case 0:
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46 | case 1: return y; /* atan(+-0,+anything)=+-0 */
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47 | case 2: return 2*pio2_hi; /* atan(+0,-anything) = pi */
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48 | case 3: return -2*pio2_hi; /* atan(-0,-anything) =-pi */
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49 | }
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50 | }
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51 | if (x == 0)
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52 | return m&1 ? -pio2_hi : pio2_hi;
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53 | if (ex == 0x7fff) {
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54 | if (ey == 0x7fff) {
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55 | switch(m) {
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56 | case 0: return pio2_hi/2; /* atan(+INF,+INF) */
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57 | case 1: return -pio2_hi/2; /* atan(-INF,+INF) */
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58 | case 2: return 1.5*pio2_hi; /* atan(+INF,-INF) */
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59 | case 3: return -1.5*pio2_hi; /* atan(-INF,-INF) */
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60 | }
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61 | } else {
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62 | switch(m) {
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63 | case 0: return 0.0; /* atan(+...,+INF) */
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64 | case 1: return -0.0; /* atan(-...,+INF) */
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65 | case 2: return 2*pio2_hi; /* atan(+...,-INF) */
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66 | case 3: return -2*pio2_hi; /* atan(-...,-INF) */
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67 | }
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68 | }
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69 | }
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70 | if (ex+120 < ey || ey == 0x7fff)
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71 | return m&1 ? -pio2_hi : pio2_hi;
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72 | /* z = atan(|y/x|) without spurious underflow */
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73 | if ((m&2) && ey+120 < ex) /* |y/x| < 0x1p-120, x<0 */
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74 | z = 0.0;
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75 | else
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76 | z = atanl(fabsl(y/x));
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77 | switch (m) {
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78 | case 0: return z; /* atan(+,+) */
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79 | case 1: return -z; /* atan(-,+) */
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80 | case 2: return 2*pio2_hi-(z-2*pio2_lo); /* atan(+,-) */
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81 | default: /* case 3 */
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82 | return (z-2*pio2_lo)-2*pio2_hi; /* atan(-,-) */
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83 | }
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84 | }
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85 | #endif
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