From help-octave-request at bevo dot che dot wisc dot edu  Wed Aug 23 14:48:40 1995
Subject: Implicit assignment within functions
From: Ted dot Harding at nessie dot mcc dot ac dot uk (Ted Harding)
To: help-octave at bevo dot che dot wisc dot edu
Date: Wed, 23 Aug 1995 20:46:57 +0200 (BST)

Hi Octavers

I discovered the following undocumented (I think) trick on a "I wonder if
that would work?" basis. It may prove useful.

Suppose you have saved variables, "X" ... , in a file "data.mat", say.

The following works:-

        function [X,...] = loadit(fname)
        eval(["load  " fname]);

    ... [ things you may want to do with the variables loaded ] ...

        endfunction

    Then executing

        [Y,...] = loadit("myfile.mat")

    will cause the variables Y,..., to be set to the values of the loaded
    variables X,..., without the necessity of making an assignment "X=..."
    within the body of the function. That is, an implicit assignment
    "X=..." has occurred during the load. "load -force " is not necessary.

Of course you have to know that the names of the variables stored in the
file are "X", etc, when defining the function "loadit" (but you have to
know this anyway, if you are going to "load" inside a function). The same
applies for further variable names. At the least I guess you save on
unnecessary duplicate usage of memory space.

One convenient usage of such a function is to load "X" from several
different files into different variables, e.g.

X0607_32 = loadit("o607_32.mat"); X0607_33 = loadit("o607_33.mat"); ...

without the re-copying the just-loaded X which you would have to do if you
did

load o607_32.mat; X0607_32 = X; load -force o607_33.mat; X0607_33 = X; etc

Best wishes,
Ted.                                    (Ted dot Harding at nessie dot mcc dot ac dot uk)