[William Park]

On Wed, Oct 11, 2000 at 10:44:20PM -0400, Tim Peters wrote:

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Likewise sqrt(-1.) needs to stop, not put a zero and keep going.

I didn't write that. Paul Dubois did.

Hmm... I don't like this. It should stop or return complex.

Paul said it should stop. You said it should stop (or return complex). So what is it that you don't like <wink/frown>? 754 mandates that sqrt(x) for x<0 return a NaN and keep going (by default) -- which even Huaiyu apparently doesn't like. [actually Tim]

I have no idea what gcc+glibc+Linux did here on 1.5.2, but it *should* have silently returned a NaN (not a zero) without setting errno if it was *self*-consistent -- anyone care to check that under -lieee?:

import math math.sqrt(-1)

NaN or ValueError? 2.0 should raise ValueError regardless of what 1.5.2 did here.).

[back to William]

It returns 'OverflowError: math range error' in 1.5.2,

Ah, that's hilarious <wink>! It's tempting to believe that glibc is violating the IEEE std despite the -lieee flag in this case, but I don't believe that's true: it's almost certainly the case that glibc is actually returning a NaN, *not* setting errno at all, and this other check in Python's mathmodule.c: #define CHECK(x) if (errno != 0) ; \ else if (-HUGE_VAL <= (x) && (x) <= HUGE_VAL) ; \ else errno = ERANGE is setting errno to ERANGE purely due to an accident of the way gcc happens to compile code for comparing NaN to Inf and -Inf.

and 'ValueError: math domain error' in 2.0.

Which is the correct exception, so is another reason for Python to avoid -lieee in 2.0. will-be-easier-to-make-it-work-right-by-design-than-to-keep-doping-out- what-happens-by-accident-now-ly y'rs - tim