Input Argument is Undefined

Hello!

I am trying to make a procedure to compute the mean of a log of probabilities. I am a beginner in Matlab so I am having a bad time finding the error. I am sure is pretty easy, but please help me!

function lik = proc1(c,K,R,c_0)
X = trnd(K,R,1)+c_0; %Generates a random sample of X from Y and the true value c_0 of size R
P = tpdf(X-ones(size(X))*c,K); %Returns the prob. of each x.
lik = mean(log(P)); %Takes the mean of the log of the probabilities

It gives me the following error:

??? Input argument "K" is undefined.
Error in ==> proc1 at 3
X = trnd(K,R,1)+c_0; %Generates a random sample of X from Y and the true value c_0 of size R 
>>

However, when I evaluate the function in the command window it works fine.

How do I stop getting this error?

[Image Analyst]

How did you call the function from your other function or script? Like, did you do something like this:

lik = proc1(1, 2, 33, 555)

or

c=41;
K=92;
c_0 = 2342;
lik = proc1(c,K,R,c_0)

or something similar? Somehow you MUST pass it arguments because you defined it such that it must. If the arguments are optional, then you can do it another way, with varargin, where you can detect input arguments and assign default values to any (or all) that are null (not supplied).