Function Reference
— Built-in Function: feval (name, ...)

Evaluate the function named name. Any arguments after the first are passed on to the named function. For example,

          feval ("acos", -1)
               3.1416

calls the function acos with the argument ‘-1’.

The function feval is necessary in order to be able to write functions that call user-supplied functions, because Octave does not have a way to declare a pointer to a function (like C) or to declare a special kind of variable that can be used to hold the name of a function (like EXTERNAL in Fortran). Instead, you must refer to functions by name, and use feval to call them.