[Newbie:] How to discard higher orders of variables?



Hello Stavros,
 
thanks for the idea. I just have to consider which multitude of variables I
might limit for my "real" problem.
 
Rolf

-----Original Message-----
From: maxima-bounces at math.utexas.edu
[mailto:maxima-bounces at math.utexas.edu]On Behalf Of Stavros Macrakis
Sent: Thursday, July 12, 2007 3:54 AM
To: Daniel Lakeland
Cc: maxima at math.utexas.edu
Subject: Re: [Maxima] [Newbie:] How to discard higher orders of variables?


Another technique to consider for multiple variables <<1 is

          taylor( ..., [x,y,z], 0, 5)

which truncates at terms beyond x^a*y^b*z^c where a+b+c > 5

e.g.

         taylor (  (k+x+y)^(1/2) - (l+x^2+y^2)^(1/4) , [x,y], 0, 1) => 

              -l^(1/4)+sqrt(k)+(sqrt(k)*x+sqrt(k)*y)/(2*k)