
Re: An independent integration test suite
Posted:
Jul 24, 2013 2:17 AM


On 7/24/2013 12:21 AM, Albert Rich wrote: > On Tuesday, July 23, 2013 2:32:20 PM UTC10, da...@axiomdeveloper.org wrote: > >> We differ on some results because Rubi (or whatever program you are using >> to create the optimal results) assumes that square roots have only a single >> positive value. Axiom does not want to make this simplification so given >> sqrt(3)*sqrt(7)*sqrt(21)  21 >> Axiom will not simplify this to zero but the Rubi test suite does. >
> Surly there must be a way to tell Axiom to choose the principal > branch so sqrt(4)2 will simplify to zero? > > Albert >
I remember reading that some math people, 100 or 200 years ago, decided that sqrt (of nonnegative, noncomplex values) was single valued function and its value is the nonnegative root (ie. principal square root).
Does any one have a reference if this is true and when this change was decided on? Or may be it always was like this?
I looked at wiki now http://en.wikipedia.org/wiki/Square_root and do not spot a date on this.
Nasser

