Last change
on this file since 403 was 337, checked in by coas-nagasima, 6 years ago |
ASP3版ECNLを追加
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File size:
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1 | /* origin: FreeBSD /usr/src/lib/msun/src/e_acosf.c */
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2 | /*
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3 | * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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4 | */
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5 | /*
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6 | * ====================================================
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7 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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8 | *
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9 | * Developed at SunPro, a Sun Microsystems, Inc. business.
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10 | * Permission to use, copy, modify, and distribute this
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11 | * software is freely granted, provided that this notice
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12 | * is preserved.
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13 | * ====================================================
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14 | */
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15 |
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16 | #include "libm.h"
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17 |
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18 | static const float
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19 | pio2_hi = 1.5707962513e+00, /* 0x3fc90fda */
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20 | pio2_lo = 7.5497894159e-08, /* 0x33a22168 */
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21 | pS0 = 1.6666586697e-01,
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22 | pS1 = -4.2743422091e-02,
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23 | pS2 = -8.6563630030e-03,
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24 | qS1 = -7.0662963390e-01;
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25 |
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26 | static float R(float z)
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27 | {
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28 | float_t p, q;
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29 | p = z*(pS0+z*(pS1+z*pS2));
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30 | q = 1.0f+z*qS1;
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31 | return p/q;
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32 | }
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33 |
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34 | float acosf(float x)
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35 | {
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36 | float z,w,s,c,df;
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37 | uint32_t hx,ix;
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38 |
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39 | GET_FLOAT_WORD(hx, x);
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40 | ix = hx & 0x7fffffff;
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41 | /* |x| >= 1 or nan */
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42 | if (ix >= 0x3f800000) {
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43 | if (ix == 0x3f800000) {
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44 | if (hx >> 31)
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45 | return 2*pio2_hi + 0x1p-120f;
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46 | return 0;
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47 | }
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48 | return 0/(x-x);
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49 | }
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50 | /* |x| < 0.5 */
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51 | if (ix < 0x3f000000) {
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52 | if (ix <= 0x32800000) /* |x| < 2**-26 */
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53 | return pio2_hi + 0x1p-120f;
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54 | return pio2_hi - (x - (pio2_lo-x*R(x*x)));
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55 | }
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56 | /* x < -0.5 */
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57 | if (hx >> 31) {
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58 | z = (1+x)*0.5f;
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59 | s = sqrtf(z);
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60 | w = R(z)*s-pio2_lo;
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61 | return 2*(pio2_hi - (s+w));
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62 | }
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63 | /* x > 0.5 */
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64 | z = (1-x)*0.5f;
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65 | s = sqrtf(z);
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66 | GET_FLOAT_WORD(hx,s);
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67 | SET_FLOAT_WORD(df,hx&0xfffff000);
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68 | c = (z-df*df)/(s+df);
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69 | w = R(z)*s+c;
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70 | return 2*(df+w);
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71 | }
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