MATLAB: How to write a fucntion which we don’t know how many “in” values will be needed

functions

I want to know how to write first line of a function which we cant tell how many variables will be "inputed".
example :
for equation 1 :
function[] = in(c1,c2,c3)
for equation 2:
function[] = in(c1,c2,c3,c4)