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Clarify that sulp expects a nonnegative input, but that +0.0 is fine.

This commit is contained in:
Mark Dickinson 2010-01-13 19:02:37 +00:00
parent b26d56ac18
commit 5818e01253
1 changed files with 7 additions and 5 deletions
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12
Python/dtoa.c
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@ -1130,11 +1130,11 @@ quorem(Bigint *b, Bigint *S)
return q;
}
/* version of ulp(x) that takes bc.scale into account.
/* sulp(x) is a version of ulp(x) that takes bc.scale into account.
Assuming that x is finite and nonzero, and x / 2^bc.scale is exactly
representable as a double, sulp(x) is equivalent to 2^bc.scale * ulp(x /
2^bc.scale). */
Assuming that x is finite and nonnegative (positive zero is fine
here) and x / 2^bc.scale is exactly representable as a double,
sulp(x) is equivalent to 2^bc.scale * ulp(x / 2^bc.scale). */
static double
sulp(U *x, BCinfo *bc)
@ -1147,8 +1147,10 @@ sulp(U *x, BCinfo *bc)
word1(&u) = 0;
return u.d;
}
else
else {
assert(word0(x) || word1(x)); /* x != 0.0 */
return ulp(x);
}
}
/* The bigcomp function handles some hard cases for strtod, for inputs