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matrices/laplacian/julia-laplaciano.jl

@@ -1,13 +1,23 @@
 using SparseArrays
 using MAT
 
-# 11 x 16
+# 20 x 20 x 20 grid
-nx = 11 - 1
+nx = 20 - 1
-ny = 16 - 1
+ny = 20 - 1
+nz = 20 - 1
+
 ex = fill(1, nx)
 ey = fill(1, ny)
+ez = fill(1, nz)
+
 Dxx = spdiagm(-1 => ex, 0 => -2 * ex, +1 => ex)
 Dyy = spdiagm(-1 => ey, 0 => -2 * ey, +1 => ey)
-L = kron(Dyy, spdiagm(0 => [ex; 1])) + kron(spdiagm(0 => [ey; 1]), Dxx);
+Dzz = spdiagm(-1 => ez, 0 => -2 * ez, +1 => ez)
+
+Ix = spdiagm(0 => [ex; 1])
+Iy = spdiagm(0 => [ey; 1])
+Iz = spdiagm(0 => [ez; 1])
+
+L = kron(Dxx, Iy, Iz) + kron(Ix, Dyy, Iz) + kron(Ix, Iy, Dzz)
 
 matwrite("laplacian-discretization-3d.mat", Dict("A" => L))