## PERSISTENT Persistent Variables

Section: Variables and Arrays

### Usage

Persistent variables are variables whose value persists between calls to a function or script. The general syntax for its use is

       persistent variable1 variable2 ... variableN

The `persistent` statement must occur before the variable is the tagged as persistent. Per the MATLAB API documentation an empty variable is created when the `persistent` statement is called.

### Example

Here is an example of a function that counts how many times it has been called.

         count_calls.m
    function count_calls
      persistent ccount
      if (~exist('ccount')) ccount = 0; end;
      ccount = ccount + 1;
      printf('Function has been called %d times\n',ccount);

We now call the function several times:

    --> for i=1:10; count_calls; end
    Function has been called 0 times
    Function has been called 0 times
    Function has been called 0 times
    Function has been called 0 times
    Function has been called 0 times
    Function has been called 0 times
    Function has been called 0 times
    Function has been called 0 times
    Function has been called 0 times
    Function has been called 0 times