Function to convert relative paths to absolute paths?

Question

I've spent quite some time to no avail looking for a built-in MATLAB function to convert relative file paths to absolute file paths (portably).

Is there one?

I'm looking for something preferably "built-in" (i.e. available somewhere in the MATLAB distribution, including one of its toolboxes). Even a "package-private" function would be acceptable, as long as I can examine the source code of function. Second best would be a third-party function, as long as it comes with a decent test suite. I am not looking for a function written in response to this question.¹

Absent any of the above, even a function to test (portably) whether a path is absolute or not would do (with the same conditions as before: either a "built-in" function or a third-party function with a test suite).

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_{¹ The difficulty with implementing such a function is not writing the function itself, but rather writing a sufficiently complete test suite for it (and, of course, making sure that the function passes all the tests!).}

Answer 1

The fullfile(pwd, relative_path) hack works well for me, but if you want something to get you the canonical form, there is no built-in (as of 2015b), but there is a well regarded downloadable script.

http://www.mathworks.com/matlabcentral/fileexchange/28249-getfullpath