Hello,

I just stumbled upon some weird behavior when trying to solve a PDE
using Laplace transform.

This is what I've done:

var ('t, z, s')
f = function ('f', z, t)
laplace (f.diff(z), t, s)

As result, I get:

s*laplace(f(t, z), t, s) - f(0, z)

which is not correct at all. Calculating by hand, I got d/dz *
laplace(f(t,z), t, s). (Applying Leibniz' rule here)

Now, if I use the exact same code as above, but change the function
definition from:

f = function ('f', z, t)

to

f = function ('f', t, z)

I get

D[0](laplace)(f(t, z), t, s)*D[1](f)(t, z)

What's going on here?

    Richard




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