I'm trying to do a basic 2D wave equation PDE in mathematica (version 11). I have a set of equations
Edit: I have infact made sure I cleared u
Clear[u]
wave2deqs = {
D[u[t, x, y], t, t] - Laplacian[u[t, x, y] , {x, y}] == 0,
u[0, x, y] == Exp[-((x - 1)^2 + (y - 1)^2)],
D[u[0, x, y], t] == 0}
This works fine except for
D[u[0, x, y], t] == 0
evaluates to 'True', and then when I put this into
wave2d = NDSolveValue[wave2deqs, u, {t, 0, 1}, {x, 0, 1}, {y, 0, 1} ]
I naturally get an error that eqlist is not a list of equations.
So my question is, why would
D[u[0, x, y], t] == 0
even evaluate to a boolean rather than being another equation?
I followed this examples for reference: https://www.wolfram.com/mathematica/new-in-10/pdes-and-finite-elements/solve-a-wave-equation-in-2d.html which is in mathematica 10, but seems ridiculous that this wouldn't work.
Clear[u]
followed byNDSolveValue
again. $\endgroup$ – Carl Woll Apr 12 '17 at 21:03u[0,x,y]
doesn't havet
, so the derivative is 0. PerhapsDerivative[1,0,0][u][0,x,y] == 0
would work better. $\endgroup$ – Carl Woll Apr 12 '17 at 21:30