ASKSAGE: Sage Q&A Forum - Latest question feedhttp://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Thu, 03 Sep 2015 16:50:54 -0500Problems in solving eigenvalue equations with differential operatorshttp://ask.sagemath.org/question/29398/problems-in-solving-eigenvalue-equations-with-differential-operators/Let's say we have a linear differential operator $\hat A = \sum_k a_k \frac {d^k} {dx^k}$ and we want to solve the eigenvalue equation $\hat A f(x) = a f(x)$ which is an ODE that we put in sage and outputs a solution $g(x)$. We now want to substitute $f(x)$ with $g(x)$ and simplify our expression in order to extract the eigenvalues of $\hat A$. The problem here is that I am not able to substitute the derivatives with my solution neither via `eqn.substitute_expression(f(x) == g(x))` nor via `eqn.substitute_function(f(x),g(x))` because `D[0]f(x)`, ... `D[0,0,...,0]f(x)` remain unchanged.
papachristoumariosThu, 03 Sep 2015 16:50:54 -0500http://ask.sagemath.org/question/29398/