EOF_SPACE(A, FRAC_TIMESER) Returns EOF (Empirical Orthogonal Function) spacial fields(eigenfunctions) from x-y-z-time field

The EOF functions all make the same computations, returning different portions of the results. EOF_SPACE returns the eigenfunctions, normalized so that they have the units of data, while time amplitude functions (TAF's) are dimensionless. Thus the sum of the values of a given EOF = sqrt(eigenvalue), and the mean of a given TAF = 1. EOF_STAT returns some useful statistics: the number of EOF's which were computed and normalized for the parameters given; the %variation explained for each eigenfunction, and the eigenvalues.

Specifying the context of the input variable explicitly e.g.

 EOF_SPACE(A[x=20:40,y=2s:40n,l=1:58],FRAC_TIMESER)

will prevent any confusion about the region. See the note in chapter 3 on the context of variables passed to functions.

The method is an implementation of Chelton's '82 method for finding EOFs of gappy time series. If there are no gaps, it reduces to ordinary EOFs.

The EOF analysis solves a matrix problem where the matrix is dimensioned (NX*NY*NZ) by NT, which can quickly become quite large. The EOF functions use other workspace as well which demands even more memory, and often memory must be increased with the SET MEMORY command. Regridding to a coarser grid or restricting the region may be necessary.

See the example under EOF_STAT for more on the input parameters, and see the demonstration ef_eof_demo.jnl for examples of this function.

Note: Earlier versions of the EOF functions had one more parameter. Check the version you have by saying

yes? SHOW FUNCTION eof*