On Thu, Oct 12, 2006 at 10:53:12AM -0400, Alan G Isaac wrote: > On Thu, 12 Oct 2006, Stefan van der Walt apparently wrote: > > I tried to explain the argument at > > http://www.scipy.org/NegativeSquareRoot > > Helpful. But you start off by saying: > In mathematics, the above assumption is true -- that > the square root of -1 is 1j. > > Since square root is (here) a function, and part of the > function definition is the domain and codomain, this > statement is not correct. If the codomain is real numbers, > the domain must correspondingly be (a subset of) the > nonnegative reals. The nan output is the result of an > **invalid** input. > > So the question is really: "Why is a negative real number an > invalid input in this implementation", or "Why in this > implementation is the type of the output restricted by the > type of the input?" You get a good start on answering that.
You are more than welcome to change the wiki if you can think of a simpler way to explain the problem... In fact, I would encourage that -- I just put it there as a starting point. Cheers Stéfan ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Numpy-discussion mailing list Numpy-discussion@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/numpy-discussion
