[issue27363] Complex with negative zero imaginary part

[Vedran Čačić]

Vedran Čačić added the comment:

Yes, but IMO that's a separate issue. And if complex analysis has taught me anything, it's that the sign of zero of .imag is much more important than the sign of zero of .real part (most elementary functions have branch cuts along real axis, where sign of .imag ensures continuity on both sides). Of course, having both would be even better, but having only this part is a good part of a good thing.

However, as I said, I know it's complicated. How about giving a "conventional" repr to complex? As far as I see, it's really not hard to implement - the only problem is backwards compatibility. But that was a problem when parentheses were added, too, right?

[ And there would be one more benefit: We could finally say goodbye to  weird "names" (infj, nanj) in the repr. By analogy with float, this could just be complex('nan', '-inf') or whatever. ]

For what it's worth, I'm not sure we should try too hard to preserve complex(repr(z)) being z given isinstance(z, complex). For example, Fraction and Decimal don't have this property (while it does kinda hold for str instead of repr, and it would continue to kinda hold for str here). Yes, I know Fraction and Decimal aren't builtins and complex is, but I really think it's only because of syntax support for j-based literals.

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue27363>
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