Re: Sqrt of complex number
- To: mathgroup at smc.vnet.net
- Subject: [mg126672] Re: Sqrt of complex number
- From: Richard Fateman <fateman at cs.berkeley.edu>
- Date: Wed, 30 May 2012 04:10:44 -0400 (EDT)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- References: <201205270842.EAA17817@smc.vnet.net> <jpvfh3$q6g$1@smc.vnet.net> <jq25u1$6gl$1@smc.vnet.net>
On 5/29/2012 2:46 AM, David Bailey wrote: ..... >> > > In addition to what others have said, it is maybe worth pointing out > that in general, the Sqrt expression would be embedded in a larger > expression, such as a+Sqrt[3-4 I]+42 - so what should Mathematica do? If > it returns a list of all possible answers, that might not be acceptable > to something that was expecting a single value, That suggests to me that whatever was expecting a single value has a bug in it. Ideally if the mathematics dictates "there are multiple answers" then a good program should be able to deal with it. Otherwise it is not doing mathematics. and anyway, expressions > such as ArcSin[.2] would have an infinite number of answers! There are several possible notations for infinite sets. Here's one: Table[f[x],x,1, Inf] > > The only possible alternative strategy would be not to evaluate at all, No, see above. > as is the case with Sqrt[x^2] (since the answer can by x or -x). Root[x^2,n] works for me, if n is an integer. We could have all even n choose one sign and odd n choose the other. These suggestions may not fit into today's Mathematica very well, but that does not mean that a better system could not be constructed. RJF > > David Bailey > http://www.dbaileyconsultancy.co.uk > >
- References:
- Sqrt of complex number
- From: Jacare Omoplata <walkeystalkey@gmail.com>
- Sqrt of complex number