L = del2(U)
L = del2(U, h)
L = del2(U, hx, hy)
| Parameter | Description |
|---|---|
| U | Input array: vector, matrix or multidimensional array. |
| h | Uniform scalar spacing between points in every direction, 1 (default). |
| hx, hy | Scalar spacing between points, hx along the columns (x direction) and hy along the rows (y direction). |
| Parameter | Description |
|---|---|
| L | Discrete Laplacian, an array the same size and class as U. |
del2(U) returns a discrete approximation of the Laplacian of U divided by 2*ndims(U).
For an interior element of a matrix, the value is the average of its four neighbours minus the element itself: L(i,j) = (U(i-1,j) + U(i+1,j) + U(i,j-1) + U(i,j+1))/4 - U(i,j).
At the borders, a second-difference extrapolation is used so that L has the same size as U.
del2(U, h) uses the uniform spacing h in every direction, and del2(U, hx, hy) uses the spacing hx along the columns and hy along the rows.
L = del2(magic(4))| Version | Description |
|---|---|
| 2.0.0 | initial version |