[Octave-bug-tracker] [bug #65134] griddata row+col vector inputs do not implicitly expand to grid

[Nicholas Jankowski]

Update of bug#65134 (group octave):

                Priority:              5 - Normal => 3 - Low                
              Item Group:    Matlab Compatibility => Undocumented Matlab    
                 Release:                   8.4.0 => dev                    

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Follow-up Comment #6:

ok. reading comprehension is finally kicking in.  Octave has always done the
query point expansion, and does it correctly, but only if it is supplied as
xi=row and yi = column. and it's right there in the help:


The interpolation points are (XI, YI).  If, and only if, XI is a
row vector and YI is a column vector, then 'meshgrid' will be used
to create a mesh of interpolation points.


matlab's docs say the same thing.

comment #0 was specifically about the fact that if you supply x as a column
vector and y as a row vector, octave doesn't do the meshgrid expansion while
Matlab does.

So yes, JWE is right, the bug report is specifically about undocumented matlab
behavior. Octave is currently following the docs, and that behavior is
currently consistent in 8.4 through dev. updating report metadata.

All of that said, griddata is generally 'legacy' for matlab, as they've
focused more on their object based interpolants (griddedInterpolant, etc), so
griddata behavior is unlikely to change any time soon. It would be fairly
simple to implement this change.  It would only break some user code in the
single case where they were supplying a column vector to x and a row vector to
y, expecting an output vector and now getting a meshgrid sized array.
workaround would be simple enough, just transposing one input vector to avoid
the problem. 




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