is readmatrix a built-in Matlab function part over every install after 2019a?

Can I assume that all functions in ...toolbox\matlab\iofun (e.g. readmatrix) are built-in Matlab and will be installed by default in any installation for that Release number?

Answer 1

[John D'Errico]

NO. Not for ANY release number. Some of those functions may have been introduced in different years, different releases. And if the function you want did not exist in an older release, then you don't get to use it.

You can learn when a function was introduced from the docs. I see that detectImportOptions was introduced in R2016b. But callSoapService was introduced before R2006a, which is pretty much beyond the view of almost every user out there. Does ANYONE still use a release that old? ;-)

It is true that future releases will all see all of those functions, and possibly more, as new utilities are introduced,. At least this is true unless some function is declared obsolete and is superceded. In that case, they give you a LOT of time to prepare for the replacement, lots of advance warning before anything disappears.

Anyway, if you have some specific function you need to be there, then you should just check the docs, and look for the release date for those functions. They always put it down at the bottom.

[Walter Roberson]

Note that readmatrix() itself has been part of basic MATLAB since R2019a.

The available options to readmatrix() have changed over time.

[Rives]

OK, thanks. I understand release versions and things evolving over time. My main question was basically is everything in ..toolbox\matlab\iofun part of basic built-in matlab. So no functions you find in that directory are paid extra toolboxes? I think that is true from what I can tell. The reason I was questioning this is because if you do:

>> which fscanf

built-in (C:\Program Files\MATLAB\R2019a\toolbox\matlab\iofun\fscanf)

>> which readmatrix

C:\Program Files\MATLAB\R2019a\toolbox\matlab\iofun\readmatrix.m

note how fscanf says "built-in" but readmatrix does not. However I just checked another install where I think we only have the signal processing tool box as the only paid toolbox and readmatrix is still there in ...toolbox\matlab\iofun\readmatrix.m

So I think readmatrix is included in every install after 2019a by default was specifically my most direct question I was trying to answer

[Walter Roberson]

fscanf() happens to be implemented in C++ code.

readmatrix() happens to be implemented largely in .m files, together with some C++ code.

readmatrix() is much more complicated than fscanf()

[John D'Errico]

Built-in functions are still part of MATLAB. It is just they are not provided as MATLAB code. For example, the function chol is a built-in function, but it is completely part of MATLAB, and always will be so. (I don't think I'm going out on a limb there.) The designation built-in does not mean a toolbox is required to get that function.

Yes. Readmatrix is part of MATLAB, and will stay that way. It was introduced in R2019a, as you have observed, and you need not worry about it disappearing, nor do you need an extra toolbox to get that function.