GNU Octave Manual Version 3by John W. Eaton, David Bateman, Søren Hauberg Paperback (6"x9"), 568 pages ISBN 095461206X RRP £24.95 ($39.95) |

### 8.2.2 Recursion

With some restrictions^{(3)}, recursive function calls are allowed. A
*recursive function* is one which calls itself, either directly or
indirectly. For example, here is an inefficient^{(4)} way to compute the factorial of a given integer:

function retval = fact (n) if (n > 0) retval = n * fact (n-1); else retval = 1; endif endfunction

This function is recursive because it calls itself directly. It eventually terminates because each time it calls itself, it uses an argument that is one less than was used for the previous call. Once the argument is no longer greater than zero, it does not call itself, and the recursion ends.

The built-in variable `max_recursion_depth`

specifies a limit to
the recursion depth and prevents Octave from recursing infinitely.

__Built-in Function:__`val`=**max_recursion_depth***()*__Built-in Function:__`old_val`=**max_recursion_depth***(*`new_val`)- Query or set the internal limit on the number of times a function may be called recursively. If the limit is exceeded, an error message is printed and control returns to the top level.

ISBN 095461206X | GNU Octave Manual Version 3 | See the print edition |