Dr. David Kirkby Ph.D CEng MIET Kirkby Microwave Ltd Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT, UK. Registered in England and Wales, company number 08914892. http://www.kirkbymicrowave.co.uk/ Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please)
On 4 June 2015 at 05:02, rjf <[email protected]> wrote: > 1. anyone who believes that sqrt(x^2) is |x| is mistaken. As Bill Page > says, there are two values. > 2. any system that automatically produces |x| can be tricked into > committing serious errors. > Currently, Maxima apparently does this. Some people consider this a > feature. Clearly we > have a difference of opinion about sqrt. Mathematica leaves the > expression unchanged. > What version of MMA leave it unevaluated? Later you say Mathematica 9 gives ln(2). For what it is worth, on Mathematica 7 Mathematica 7.0 for Sun Solaris x86 (64-bit) Copyright 1988-2009 Wolfram Research, Inc. In[1]:= Sqrt[x^2] 2 Out[1]= Sqrt[x ] 3. I tried Maxima 5.23.2 on the integral and got log(-1) which is > nonsense. > > 4. Mathematica 9 answers ln(2). > As a non-mathematician, I feel it would be useful if there were arbitrary choices of branch cuts, then the software should 1) Pick one, but print it in orange. 2) Print a warning in red 3) All subsequent expressions were printed in orange, to indicate there are possible ambiguities. Dave -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
