Should numpy.sqrt(-1) return 1j rather than nan?

A. M. Archibald peridot.faceted at gmail.com
Thu Oct 12 11:07:09 CDT 2006


On 12/10/06, David Goldsmith <David.L.Goldsmith at noaa.gov> wrote:

> I don't use scipy (and don't want to because of the overhead) but it
> sounds like I should because if I'm taking the square root of a variable
> whose value at run time happens to be real but less than zero, I *want*
> the language I'm using to return an imaginary; in other words, it's not
> the scipy behavior which "scares" me, its the numpy (which I do/have
> been using) behavior.  To which you might say, "Well, if that's what you
> want, and you have Matlab (as you've said you do), then just use that."
> But that's precisely the point: people who don't want to be bothered
> with having to be "a bit more care[ful]" (as Chuck put it) - and who can
> afford it - are going to be inclined to choose Matlab over numpy.
> Perhaps one doesn't care - in the grand scheme of things, it certainly
> doesn't matter - but I think that you all should be aware that this
> numpy "feature" will be seen by many as more than just a nuisance.

Scipy doesn't do what you want. What you want is to use complex
numbers throughout; then numpy and scipy will do exactly what you
request.

A. M. Archibald

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