Dear colleagues,
I try to verify the accuracy of the solution
y(x,t) = f(x+c*t)+g(x-c*t)
to the classical wave partial differential equation. (Analogously,
with the Laplace equation.) I prepared the code and
found the solutions (such as the above one for the wave
equation), but now I wish to proceed with the verification
through differentations by using Maxima.
My impression would be that Maxima can find that
(d/dx)f(2*x) = 2*f '(2*x),
but it failed. Therefore the above verification and similar
verifications cannot succeed since Maxima seems not
knowing the chain rule for not concrete functions (contrary
to Maple and Mathematica). Is this true with my command
diff(f(2*x),x)
that I tried to use or some trivial error (due to me) is
present in this so simple Maxima command?
It is understood that the differentiation algorithms of
Maxima can be easily extended if required, but, never-
theless, I would prefer that the chain rule in the present
case could also be available to Maxima in advance.
Your help will be greatly appreciated.
Many thanks in advance and best regards from Patras,
Nikos