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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libquadmath/] [math/] [sqrtq.c] - Blame information for rev 740

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Line No. Rev Author Line
1 740 jeremybenn
#include "quadmath-imp.h"
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#include <math.h>
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#include <float.h>
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__float128
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sqrtq (const __float128 x)
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{
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  __float128 y;
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  int exp;
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  if (x == 0)
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    return x;
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  if (isnanq (x))
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    return x;
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  if (x < 0)
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    return nanq ("");
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  if (x <= DBL_MAX && x >= DBL_MIN)
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  {
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    /* Use double result as starting point.  */
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    y = sqrt ((double) x);
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    /* Two Newton iterations.  */
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    y -= 0.5q * (y - x / y);
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    y -= 0.5q * (y - x / y);
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    return y;
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  }
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#ifdef HAVE_SQRTL
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  if (x <= LDBL_MAX && x >= LDBL_MIN)
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  {
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    /* Use long double result as starting point.  */
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    y = sqrtl ((long double) x);
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    /* One Newton iteration.  */
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    y -= 0.5q * (y - x / y);
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    return y;
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  }
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#endif
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  /* If we're outside of the range of C types, we have to compute
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     the initial guess the hard way.  */
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  y = frexpq (x, &exp);
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  if (exp % 2)
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    y *= 2, exp--;
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  y = sqrt (y);
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  y = scalbnq (y, exp / 2);
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  /* Two Newton iterations.  */
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  y -= 0.5q * (y - x / y);
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  y -= 0.5q * (y - x / y);
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  return y;
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}
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