An EOF operator for CliMAF and multi-variable outputs

[jservonnat]

The computation of EOFs comes with an issue: we normally have two outputs from an EOF decomposition (the eigenvectors and the principal components). We might also need to have access to the eigenvalues (explained variance). Therefore two strategies are possible:

• we say that climaf only handles one-variable output files and we try to find a solution to produce the EOFs, the principal components and the eigenvalues separately (cdo might be able to do that)
• we produce one netcdf with more than one variable (in this case, three) Discussion is open!

[senesis]

See http://climaf.readthedocs.org/en/latest/std_operators.html under bullet "example for two outputs"

[senesis]

What I implemented (and referenced above) is not in line with your proposals , but is an alternate way, laready usable. This does not close the discussion We may also whish to have a compiste operator which perfomrs both EOF computation and some standard graphic production (which would show first few ranks PC and EOF, and also explained variances, as already implemented in CAMI). We cannot yet mix grpahic and numeric outputs for a CliMAF operator