How to set a default value for my custom function

I hope to create such custom function

function addnum(mat,n=numel(mat))
mat+n

I mean I try to add a number into the element of mtrix mat,but if I don't give a explicit value for n,I hope the n will be the number of the mtrix self.

Answer 1

[Stephen23]

Unfortunately MATLAB does not (currently) allow defining default values in the function definition line itself (nor does it allow arguments to be specified by name, only by position). To define a default value you can use the input parser class (I find this slow and pointlessly complex), or simply use nargin like this:

function out = addnum(mat,n)
if nargin<2
  n = 3;
end
out = mat+n;
end

For more multiple optional arguments you should consider using a structure or name-value pairs: see my FEX submission num2words for an example of this.

Answer 2

[KSSV]

function addnum(mat)
n=numel(mat)
mat+n

[Yode]

Thanks man,but I hope addnum(mat,3) works either,then every element will add 3. :)

[KSSV]

yes..

[Yode]

@KSSV Sorry,that work for you ?

[KSSV]

function addnum(mat)
n=numel(mat)
mat+n

If you are using the above one....don't send any input just call it by addnum(mat), if you want logically select n then follow Stephen Cobeldick suggested.

Answer 3

[Lee]

This is the way to define default number in matlab

function addnum(mat,n)
    arguments
        mat
        n=numel(mat)
    end
    mat+n
end

Be sure to list all arguments in order