The 2D Wave Equation on a Square;

Homogeneous Neumann Boundary Conditions

 $1$ $cos\left(t\right) cos\left(x\right)$ $cos\left(2t\right) cos\left(2x\right)$ $cos\left(3t\right) cos\left(3x\right)$ $cos\left(t\right) cos\left(y\right)$ $cos\left(21/2t\right) cos\left(x\right) cos\left(y\right)$ $cos\left(51/2t\right) cos\left(2x\right) cos\left(y\right)$ $cos\left(101/2t\right) cos\left(3x\right) cos\left(y\right)$ $cos\left(2 t\right) cos\left(2y\right)$ $cos\left(51/2t\right) cos\left(x\right) cos\left(2y\right)$ $cos\left(81/2t\right) cos\left(2x\right) cos\left(2y\right)$ $cos\left(131/2t\right) cos\left(3x\right) cos\left(2y\right)$ $cos\left(3 t\right) cos\left(3y\right)$ $cos\left(101/2t\right) cos\left(x\right) cos\left(3y\right)$ $cos\left(131/2t\right) cos\left(2x\right) cos\left(3y\right)$ $cos\left(181/2t\right) cos\left(3x\right) cos\left(3y\right)$

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