Hi, what should I do to get the 'Not enough input arguments'-error,

If I call my own function with not enough input arguments MATLAB realizes this not until the missing variable is used.

Example:

function d = inputErrorCheck(a,b,c)

if a > b 
    d = a+b;
else
    d = a+c;
end;    

end

Output:

>> inputErrorCheck(3,2)

ans = 5

>> inputErrorCheck(2,3)

Not enough input arguments.

Error in inputErrorCheck (line 6) d = a+c;

Is there a setting or something to get MATLAB to check the amount of input arguments before it starts the function?

Thanks!

Answer 1

[Clemens Lindscheid]

Hi Rebecca,

your problem seems to be closely related to the question of strict data typing for function arguments in Matlab. As far as I know, you cannot do it automatically in Matlab. Matlab functions usually start with checking the number and data type of the input arguments manually, see e.g. gaussmf from the statistics toolbox with 7 lines of checking input arguments and 2 lines of actual code (R2014b).

There are several ways of checking the input arguments:

• Using nargin (or narginchk), is* and error. Check the Fundamental MATLAB Classes to get a feeling of the checks you need to perform.
• Using the validateattributes function.
• Using the inputParser class.
• Using try catch
• Compile it as a mex-function. You will need to specify the datatypes before compiling.

Answer 2

[Mischa Kim]

Rebecca, yes. Use something like

function d = inputErrorCheck(a,b,vargin)

switch nargin
    case 3
        if a > b
            d = a + b;
        else
            d = a + vargin;
        end
    case 2
        d = a + b;      
end
end

[Rebecca Sippel]

Hi Mischa, thanks for your answer but this is not exactly what I am searching for. Maybe my question was to vague.

The third variable should not be optional. The function must not be started if there aren't enough input arguments. I don't have the problem with too many arguments because MATLAB checks this.

Example:

>> inputErrorCheck(2,3,4,5)

Error using inputErrorCheck Too many input arguments.

I know that narginchk(a,b) exists but I don't want to use it in every function. I was looking for a kind of setting in MATLAB itself to autocheck if there are not enough variables like it works with too many variables.

[Jan]

@Rebecca: There cannot be a switch in Matlab to restrict the number of inputs, because many built-in functions use optional arguments. It is a typical programming style in Matlab.