RE: Sqrt problems

*To*: mathgroup at smc.vnet.net*Subject*: [mg19522] RE: [mg19504] Sqrt problems*From*: "Ersek, Ted R" <ErsekTR at navair.navy.mil>*Date*: Sun, 29 Aug 1999 03:00:40 -0400*Sender*: owner-wri-mathgroup at wolfram.com

Rita Bijlsma wrote: ------------------------ I'm working with the textual version of mathematica 2.2 on VMS and I have some questions related to Sqrt PowerExpand[%15] 2 2 4 4 4 1 n Pi Sqrt[4 Dq + n Pi ] - - ------ + -------------------- 2 2 2 4 Dq 4 Dq - How do I get mathematica to give me: 2 2 4 4 1 n Pi 1 n Pi - - ------ + Sqrt[- + ------] 2 2 4 4 4 Dq 16 Dq <snip> (* and several other broad questions. *) ------------------------------- The following should help with one of your problems. In[1]:= 1/2 - (n^2*Pi^2)/(4*Dq^2) + Sqrt[4*Dq^4 + n^4 + Pi]/(4*Dg^2)/. a_ Sqrt[b_]:>Sqrt[a^2 *b] Out[1]= 1/2 - (n^2*Pi^2)/(4*Dq^2) + Sqrt[(4*Dq^4 + n^4 + Pi)/Dg^4]/4 This pattern matching stuff takes some practice before you get good at it. I have a section on Pattern matching on the web page I mention below. You can download the whole notebook if you want. -------------------- Regards, Ted Ersek For Mathematica tips, tricks see http://www.dot.net.au/~elisha/ersek/Tricks.html