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9.2 Persistent Variables

A variable that has been declared persistent within a function will retain its contents in memory between subsequent calls to the same function. The difference between persistent variables and global variables is that persistent variables are local in scope to a particular function and are not visible elsewhere.

A variable may be declared persistent using a persistent declaration statement. The following statements are all persistent declarations.

     persistent a
     persistent a b
     persistent c = 2
     persistent d = 3 e f = 5

The behavior of persistent variables is equivalent to the behavior of static variables in C. The command static in octave is also recognized and is equivalent to persistent. Unlike global variables, every initialization statement will re-initialize the variable. For example, after executing the following code

     persistent pvar = 1
     persistent pvar = 2

the value of the persistent variable pvar is 2.