Erik Max Francis wrote: > Steven D'Aprano wrote: > > >>Perhaps you meant to write (-1)**0.5, in which case Python developers have >>a decision to make: should it assume real-valued maths unless explicitly >>told differently, and hence raise an exception, or coerce the result to >>complex? >> >>In this case, Python raises an exception, as it should, unless you >>explicitly uses complex numbers. That's the best behaviour for the >>majority of people: most people don't even know what complex numbers are, >>let alone want to deal with them in their code. Python, after all, is not >>Mathematica. > > > Note that cmath.sqrt returns the expected complex result for > cmath.sqrt(-1.0). > >>> import cmath >>> cmath.sqrt(-1) 1j >>>
Indeed. But even exponentiation can come respectably close: >>> (-1+0j)**0.5 (6.123233995736766e-17+1j) regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC www.holdenweb.com PyCon TX 2006 www.python.org/pycon/ -- http://mail.python.org/mailman/listinfo/python-list
