How to write if statement?

How do I write an if statement saying if either input is a matrix, my program should throw a unique error message? (I cannot use isvector function, I think I am supposed to use length() or size() functions if that is possible). Thank you!

[Walter Roberson]

How do you define matrix for this purpose? Which of these are a matrix ?

zeros(0,0)
zeros(0,1)
zeros(0,10)
zeros(1,0)
zeros(1,1)
zeros(1,10)
zeros(10,10)
zeros(0,0,0)
zeros(0,10,10)
zeros(10,0,10)
zeros(10,10,0)
zeros(1,10,10)
zeros(10,1,10)
zeros(10,10,1)
zeros(10,10,10)