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