# fourlap.m

From Spinach Documentation Wiki

Fourier spectral representation of the Laplacian acting on a 3D data array. Fourier spectral differentiation operators are exact on a given grid when the data array satisfies the Larmor condition on that grid.

## Contents

## Syntax

L=fourlap(npoints,extents)

## Arguments

npoints - a three-element vector specifying the number of discretization points in each dimension of the 3D cube of data that the operator will be acting on, ordered as [X Y Z]. extents - a three-element vector specifying axis extents, ordered as [X Y Z].

## Outputs

L - Fourier spectral Laplacian, a sparse matrix designed to act on the vectorization of the 3D data array. The dimensions of the data array are assumed to be ordered as [X Y Z].

## Notes

Periodic boundary conditions.

## See also

fdmat.m, fdvec.m, hydrodynamics.m, fdhess.m, fdkup.m, fourdif.m, fftdiff.m

*Version 2.1, authors: Ilya Kuprov*