where is worldToSubscript in R2019a?

I'm running Matlab R2019A. If I type "doc worldToSubscript", it brings up the documentation for this function in the on-line help, which can also be viewed on this page:

https://www.mathworks.com/help/images/ref/imref2d.worldtosubscript.html

This documentation indicates that this method is part of the Image Processing Toolbox, even though its function, similarity to other functions, and dependency on spatial reference objects suggests that it should be part of the mapping toolbox. However, if I type "help worldToSubscript", or try to invoke it, Matlab tells me it's not found. Where is it?

[Walter Roberson]

It is a "method" of the image referencing object class. It is not available by itself, only if an image reference object is passed in.

[Chris Volpe]

But where is it??? "Help" can't find it, but has no problem finding "worldToIntrinsic". They both take a spatial referencing object as a parameter. And when I try to invoke worldToSubscript per the documentation, matlab throws an error because the function doesn't exist.

Answer 1

[Walter Roberson]

edit(fullfile(toolboxdir('images/images'), 'imref2d.m'))

and look at approximately line 275.

This requires the Image Processing Toolbox, R2013a or later.

[Chris Volpe]

Thank you!

I'm still a bit confused as to why "help" can't find it. (I have the IP toolbox.) Help has no problem locating methods in classes in the mapping toolbox, for example:

>> which worldToSubscript
'worldToSubscript' not found.
>> which sizesMatch
C:\Program Files\MATLAB\R2019a\toolbox\map\map\+map\+rasterref\MapRasterReference.m  % map.rasterref.MapRasterReference method

And it has no problem with other functions in the IP toolbox:

>> which imerode
C:\Program Files\MATLAB\R2019a\toolbox\images\images\imerode.m

[Walter Roberson]

I just tested in R2019a. At first it could not find either help, but as soon as I asked for it directly it could find it in short form.

help sizesMatch   %could not find
help worldToSubscript  %could not find
help imref2d/worldToSubscript  %okay
help sizesMatch   %found it this time
help worldToSubscript %found it this time

That is, MATLAB does not load the class details until the class is referenced once, either by using it in a function or by calling upon help for the class (my testing shows that help imref2d also makes help for the methods available.)

[Chris Volpe]

That did it! I did a "help imref2d" and THEN a "help worldToSubscript", and it worked! Thanks for solving this mystery!