Function with mismatched inputs?

I am going over someone's code and in their main file they call a function as such:

[ar] = function(ar, data(i+1,1), data(i,1), data(i+1,2), data(i+1,4), dt);

However, in the function file there are many more expected inputs:

function [ theta1,time1 ] = function(t,y,u,theta0,x0,dt,V_x,V_w,V_v,V_theta,V_r,V_e)

I'm not completely sure if this code runs, but is this valid code?

[per isakson]

Try

>> cssm(1)
  Name      Size            Bytes  Class     Attributes
  x1        1x1                 8  double              

>> cssm(1,2)
  Name      Size            Bytes  Class     Attributes
  x1        1x1                 8  double              
  x2        1x1                 8  double              

>> cssm
>> 

>> cssm([],2)
  Name      Size            Bytes  Class     Attributes
  x1        0x0                 0  double              
  x2        1x1                 8  double

where

function    [y1,y2] = cssm(x1,x2,x3)
    whos
end

Answer 1

[Walter Roberson]

Yes, declaring extra input arguments is fine, as long as the code does not use any argument that is not passed. The nargin() call helps determine how many arguments were actually passed, and you can use exist() to determine whether an individual parameter was passed.

[per isakson]

"declaring extra input arguments is fine" &nbsp However, I fail to find this explicitly stated in the documentation.

[Walter Roberson]

http://www.mathworks.com/help/matlab/matlab_prog/create-functions-in-files.html

Tip   When you define a function with multiple input or output arguments, list any required arguments first. This allows you to call your function without specifying optional arguments.

http://www.mathworks.com/help/matlab/matlab_prog/find-number-of-function-arguments.html

This example shows how to determine how many input or output arguments your function receives using nargin and nargout.

[per isakson]

Yes, that might be the best information on "extra input" in the documentation, but I wouldn't say it's explicit.

Answer 2

[Image Analyst]

It's true that you don't have to supply all declared arguments, but if you don't supply them all, then inside the function you'll need to check nargin for that condition and assign default values for the missing input arguments if they will be needed somewhere in the function. Like if a windowSize is optional and if they don't pass it in you want to use a value of 3, then you can say

if nargin < 5 % (or wherever it falls in the arg list)
    windowSize = 3;  % Assign default value.
end