Help with using "nargin"

Hi All,

I got a function "replace(a,b,c)" where I am trying to replace input arguments with another input argument when some of them are omitted. e.g. If c is omitted, I need to replace a with 2 copies of b and if b is also omitted, a needs to be replaced with 2 zeros. I tried to use nargin, but haven't been successful, can anyone help me on what I am doing wrong?

function replace(a,b,c)
if nargin<2
    a=0;
end
if nargin<3
    a=b;
end

Thanks.

Answer 1

[James Tursa]

Think about what happens in your code if nargin == 1. In that case, b does not exist, but you get into the nargin<3 test and try to use b. So this will fail.

Your words are not entirely clear to me, but here is a guess at what you might want:

function replace(a,b,c)
if nargin < 2
    a = 0;
    b = 0;
    c = 0;
elseif nargin < 3
    a = b;
    c = 0;
end

2nd attempt at coding verbatim what you requested:

function replace(a,b,c)
if nargin < 2
    a = [0 0];
elseif nargin < 3
    a = [b b];
end