y = sum(x)
x=[1 2 3 5]

is not that true, i am confused.

You haven't stated the *Function* name, input values and output values. Without them the code from the site cannot check your code.

Secondly you've declared X after you wanted to run a function with it.

The program will read:

Sum of X equals Y. X equals Zero or Not a Number, therefore Y is Zero or Not a Number. Next line, X is [Array]. Okay, X is [Array].

Also good practice to end your functions with a semicolon ;

;)

You haven't stated the *Function* name, input values and output values. Without them the code from the site cannot check your code. Secondly you've declared X after you wanted to run a function with it. The program will read: Sum of X equals Y. X equals Zero or Not a Number, therefore Y is Zero or Not a Number. Next line, X is [Array]. Okay, X is [Array]. Y is still 0 or NaN. Also good practice to end your functions with a semicolon ;