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annotate libquadmath/math/sqrtq.c @ 68:561a7518be6b

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update gcc-4.6
author Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
date Sun, 21 Aug 2011 07:07:55 +0900
parents
children 04ced10e8804
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rev   line source
68
561a7518be6b update gcc-4.6
Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
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1 #include "quadmath-imp.h"
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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2 #include <math.h>
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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3 #include <float.h>
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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4
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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5 __float128
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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6 sqrtq (const __float128 x)
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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7 {
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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8 __float128 y;
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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9 int exp;
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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10
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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11 if (x == 0)
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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12 return x;
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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13
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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14 if (isnanq (x))
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
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15 return x;
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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16
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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17 if (x < 0)
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
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18 return nanq ("");
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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19
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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20 if (x <= DBL_MAX && x >= DBL_MIN)
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
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21 {
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
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22 /* Use double result as starting point. */
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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23 y = sqrt ((double) x);
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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24
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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25 /* Two Newton iterations. */
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
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26 y -= 0.5q * (y - x / y);
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
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27 y -= 0.5q * (y - x / y);
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
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28 return y;
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
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29 }
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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30
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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31 #ifdef HAVE_SQRTL
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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32 if (x <= LDBL_MAX && x >= LDBL_MIN)
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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33 {
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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34 /* Use long double result as starting point. */
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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35 y = sqrtl ((long double) x);
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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36
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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37 /* One Newton iteration. */
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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38 y -= 0.5q * (y - x / y);
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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39 return y;
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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40 }
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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41 #endif
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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42
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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43 /* If we're outside of the range of C types, we have to compute
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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44 the initial guess the hard way. */
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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45 y = frexpq (x, &exp);
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
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46 if (exp % 2)
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
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47 y *= 2, exp--;
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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48
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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49 y = sqrt (y);
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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50 y = scalbnq (y, exp / 2);
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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51
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
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52 /* Two Newton iterations. */
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
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53 y -= 0.5q * (y - x / y);
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
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54 y -= 0.5q * (y - x / y);
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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55 return y;
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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56 }
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Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
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57