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author | Ben Cheng <bccheng@google.com> | 2012-10-01 10:30:31 -0700 |
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committer | Ben Cheng <bccheng@google.com> | 2012-10-01 10:30:31 -0700 |
commit | 82bcbebce43f0227f506d75a5b764b6847041bae (patch) | |
tree | fe9f8597b48a430c4daeb5123e3e8eb28e6f9da9 /gcc-4.7/libquadmath/math/sqrtq.c | |
parent | 3c052de3bb16ac53b6b6ed659ec7557eb84c7590 (diff) | |
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Initial check-in of gcc 4.7.2.
Change-Id: I4a2f5a921c21741a0e18bda986d77e5f1bef0365
Diffstat (limited to 'gcc-4.7/libquadmath/math/sqrtq.c')
-rw-r--r-- | gcc-4.7/libquadmath/math/sqrtq.c | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/gcc-4.7/libquadmath/math/sqrtq.c b/gcc-4.7/libquadmath/math/sqrtq.c new file mode 100644 index 000000000..6ed4605ed --- /dev/null +++ b/gcc-4.7/libquadmath/math/sqrtq.c @@ -0,0 +1,57 @@ +#include "quadmath-imp.h" +#include <math.h> +#include <float.h> + +__float128 +sqrtq (const __float128 x) +{ + __float128 y; + int exp; + + if (x == 0) + return x; + + if (isnanq (x)) + return x; + + if (x < 0) + return nanq (""); + + if (x <= DBL_MAX && x >= DBL_MIN) + { + /* Use double result as starting point. */ + y = sqrt ((double) x); + + /* Two Newton iterations. */ + y -= 0.5q * (y - x / y); + y -= 0.5q * (y - x / y); + return y; + } + +#ifdef HAVE_SQRTL + if (x <= LDBL_MAX && x >= LDBL_MIN) + { + /* Use long double result as starting point. */ + y = sqrtl ((long double) x); + + /* One Newton iteration. */ + y -= 0.5q * (y - x / y); + return y; + } +#endif + + /* If we're outside of the range of C types, we have to compute + the initial guess the hard way. */ + y = frexpq (x, &exp); + if (exp % 2) + y *= 2, exp--; + + y = sqrt (y); + y = scalbnq (y, exp / 2); + + /* Two Newton iterations. */ + y -= 0.5q * (y - x / y); + y -= 0.5q * (y - x / y); + return y; +} + |