I'm getting a confusing error message.

FUNCTION Add new function. New functions may be added to MATLAB's vocabulary if they are expressed in terms of other existing functions. The commands and functions that comprise the new function must be put in a file whose name defines the name of the new function, with a filename extension of '.m'. At the top of the file must be a line that contains the syntax definition for the new function. For example, the existence of a file on disk called stat.m with: function [mean,stdev] = stat(x) %STAT Interesting statistics. n = length(x); mean = sum(x) / n; stdev = sqrt(sum((x - mean).^2)/n); defines a new function called STAT that calculates the mean and standard deviation of a vector. The variables within the body of the function are all local variables. See SCRIPT for procedures that work globally on the work- space. A subfunction that is visible to the other functions in the same file is created by defining a new function with the FUNCTION keyword after the body of the preceding function or subfunction. For example, avg is a subfunction within the file stat.m: function [mean,stdev] = stat(x) %STAT Interesting statistics. n = length(x); mean = avg(x,n); stdev = sqrt(sum((x-avg(x,n)).^2)/n); %------------------------- function mean = avg(x,n) %AVG subfunction mean = sum(x)/n; Subfunctions are not visible outside the file where they are defined. You can terminate any function with an END statement but, in most cases, this is optional. END statements are required only in MATLAB files that employ one or more nested functions. Within such a file, every function (including primary, nested, private, and subfunctions) must be terminated with an END statement. You can terminate any function type with END, but doing so is not required unless the file contains a nested function. Normally functions return when the end of the function is reached. A RETURN statement can be used to force an early return. See also SCRIPT, RETURN, VARARGIN, VARARGOUT, NARGIN, NARGOUT, INPUTNAME, MFILENAME. Documentation for function doc function Folders named function graphics/function