Doing a symbolic Comparison of Coefficients for arbitrary length of coefficients

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FBBVC
FBBVC 2020-3-7
回答： Walter Roberson 2020-3-7
Hello Folks,
I need to do a comparison of coefficients with an arbitray number of coeeficients. For example, Imagine the following PDE: with an initial function: . Inserting this into the PDE, derivate and solving yields a very long equation with different variations of sin/cos. Now here comes the question: How can I do (symbolic) comparison of coefficients, such that I get the following equations (only exemplary):
After receiving the equations, I want to transfer them into a system of equations. I read something about determining the coefficients by matlab itself, but I guess it is a problem that the number of coefficients depend on the length of my initial function. Is there any possibility to do this?
Thanks in advance!

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Walter Roberson
Walter Roberson 2020-3-7
You can subs() a variable for the expression cos(n*t) and then you can use coeffs() to extract the coefficients that it is multiplied by.

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