x=var('x')#3.  
y=function('y',x)
DE=diff(y,x,x)+2*diff(y,x)+y-exp(-x)*cos(x)
desolve(DE,[y,x])

SageDays/Kreyszig-2.10-3 (last edited 2010-08-09 14:11:13 by ManjushaJoshi)