Octave Programming Tutorial/Writing functions

Syntax

In Octave, function definitions use the following syntax:

 function [return value 1, return value 2, ... ] = name( [arg1, arg2, ...] )
     body
 endfunction

Examples

Factorial Function

The factorial function, which takes exactly one argument and returns one integer, is as follows.

 function result = factorial( n )
     if( n == 0 )
         result = 1;
         return;
     else
         result = prod( 1:n );
     endif
 endfunction

Save m-File

You can save the definition of the function in your working directory. Use the name of the function also for the filename - e.g. use the filename factorial.m for the definition of the function factorial .

Maximum and Minimum of two integer Values

The following function, maxmin, returns the maximum and minimum value of two integers:

 function [max,min] = maxmin( a, b )
    if(a >= b )
         max = a;
         min = b;
         return;
    else
         max = b;
         min = a;
         return;
    endif
 endfunction

To call a function with multiple arguments, you specify multiple variables to hold the results. For example, one could write:

 [big,small] = maxmin(7,10);

After executing, the variable 'big' would store the value '10' and the variable 'small' would store '7'. If fewer than two variables are used to hold the result then fewer outputs are returned. Writing

a = maxmin(13,5)

would store 13 in the variable 'a', and would discard the value of 5.

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