How do you reset a persistent variable?

The documentaiton says that a persistent variable is reset when the function is cleared from memory. Why then do I not see the persistent variable update in the following?

fun(10)

y = 10

clear fun

fun(12)

y = 10

function fun(x)

  persistent y
  if isempty(y)
      y=x;
  end

  y,
  
end

[dpb]

Is function fun in its own m-file?

What does

which -all fun

return? Is there an aliased version perhaps?

Does rehash after the clear command make any difference?

I neither of the first two is the cause, then it would seem a bug. Which release?

I was/am in the middle of a debug session so didn't want to 'spearmint...

[Matt J]

All code shown is in a single mfile. fun() is a local function.

[dpb]

That's the problem...from the doc for clear the input description includes--

"Names of variables, scripts, functions, or MEX-functions to clear, specified as one or more character vectors or string scalars.

If name is a:

Function, then clear reinitializes any persistent variables in the function. Specifying a local or nested function is not supported. (emphasis added --dpb)

..."

Put fun in its own m-file and then retest.

[Matt J]

Yep. Always read the fine print, I guess.

[dpb]

If you don't want to make fun an externally-visible function, then you'll have to have a flag variable and call the function with it to reset the persistent variable within the local function.

I have a bunch of short functions that set local working directories, etc., for specific workflows that use persistent variables to retain prior working directory and other key pieces on an 'EXIT' function...one of the pieces of those is the ability to reset those on demand. I hadn't thought of using clear for that purpose, though, with them as a shorthand invocation path.

Answer 1

[Matt J]

dpb 's answer resolved it..