2020-08-04 22:58:53 +0200 received badge ● Popular Question (source) 2018-08-13 19:13:13 +0200 received badge ● Good Question (source) 2018-08-11 09:05:03 +0200 received badge ● Scholar (source) 2018-08-09 14:17:29 +0200 commented answer arrange an expression in powers of a variable Thanks! How to access the coefficients of each power? If you noticed, I am trying to use Sage for asymptotic analysis of DE's. Is there any guide/doc for this topic? 2018-08-09 14:08:34 +0200 received badge ● Supporter (source) 2018-08-08 19:38:44 +0200 received badge ● Nice Question (source) 2018-08-08 10:48:58 +0200 received badge ● Student (source) 2018-08-08 10:33:57 +0200 asked a question arrange an expression in powers of a variable I have the following code: f0 = function('f0')(x) f1 = function('f1')(x) var('ep') y = f0+ep*f1 de=ep*diff(y,x,2)+diff(y,x) expand(de)  which gives the output: ep^2*diff(f1(x), x, x) + ep*diff(f0(x), x, x) + ep*diff(f1(x), x) + diff(f0(x), x)  How can I rearrange this expression in powers of "ep" parameter? i.e ep^2*diff(f1(x), x, x) + ep*( diff(f0(x), x, x) + diff(f1(x), x) ) + diff(f0(x), x)  Then I want to get the coefficient for each power (which is a differential eq) and then pass it to the desolve.