Re: Sqrt[Sin^2(x)]=Sin(x)....????
- To: mathgroup at smc.vnet.net
- Subject: [mg16353] Re: [mg16329] Sqrt[Sin^2(x)]=Sin(x)....????
- From: Ranko Bojanic <bojanic at math.ohio-state.edu>
- Date: Thu, 11 Mar 1999 02:16:34 -0500
- Organization: Ohio State University
- Sender: owner-wri-mathgroup at wolfram.com
The result returned by Mathematica In[1]:= Sqrt[a^2]//PowerExpand Out[1]= a is clearly correct only if a is a nonnative number. The only correct answer should be In[2]:= Sqrt[a^2]//PowerExpand Out[2]= Abs[a] Regards, Ranko > Alessandro Agresti <agresti at fi.infn.it> schrieb: >> Can I get the following result: >> Sqrt[Sin^2(x)]=Sin(x) ??? >> If so, how?? >> Thanks You for Your BIG help. >> Alessandro Agresti > Alessandro, > Mathematica knows, that this isn't always true. But you can use > PowerExpand to get what you want: > In[1]= Sqrt[Sin[x]^2]//PowerExpand > Out[1]= Sin[x] > es gruesst > Peter > In a message dated 3/5/99 8:09:48 AM, agresti at fi.infn.it writes: >> Can I get the following result: >> Sqrt[Sin^2(x)]=Sin(x) ??? >> If so, how?? > Alessandro, > You have the exponent in the wrong position > Sqrt[Sin[x]^2] // PowerExpand > Sin[x] > Bob Hanlon > Alessandro, > let's hope you know what you are doing. > In[1]:= PowerExpand[Sqrt[Sin[x]^2] == Sin[x]] > Out[1]= True > Jurgen > Alessandro Agresti wrote: > >> Can I get the following result: >> Sqrt[Sin^2(x)]=Sin(x) ??? >> If so, how?? >> Thanks You for Your BIG help. >> Alessandro Agresti