From 5818e0125395b88b5e3c69dacdb50d5562628cd2 Mon Sep 17 00:00:00 2001 From: Mark Dickinson Date: Wed, 13 Jan 2010 19:02:37 +0000 Subject: Clarify that sulp expects a nonnegative input, but that +0.0 is fine. --- Python/dtoa.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/Python/dtoa.c b/Python/dtoa.c index 504ad1f..e953f09 100644 --- a/Python/dtoa.c +++ b/Python/dtoa.c @@ -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 -- cgit v0.12