Re: How to get sqrt(Year^2)===Year?
- To: mathgroup at smc.vnet.net
- Subject: [mg76001] Re: How to get sqrt(Year^2)===Year?
- From: Szabolcs <szhorvat at gmail.com>
- Date: Mon, 14 May 2007 05:49:02 -0400 (EDT)
- Organization: University of Bergen
- References: <f1s1v4$fip$1@smc.vnet.net> <f1upol$8hr$1@smc.vnet.net> <f26na5$421$1@smc.vnet.net>
Hatto von Aquitanien wrote:
>> Simplify[x==Sqrt[x^2],x>0]
>>
>> hope this helps, Daniel
>
> Well, it helps in this circumstance. I believe Convert will do the same,
> but I'm not sure if it works in all circumstances.
In what circumstances?
> I do wish there were
> some way for Mathematica to know that something such as a physical constant
> is real and positive.
You didn't mention that you want to treat Year as a unit.
> Perhaps doing that under all circumstances would
> turn into a major performance hit, but it would be nice in circumstances in
> which it is inappropriate to consider cases of x < 0, or x not real in
> Sqrt[x].
$Assumptions = {Year > 0}