Finding Nonzero Elements in a Vector

In a assignment I am working on, we are tasked with writing a MATLAB function that takes as input a nonempty vector v and returns the product of the nonzero elements in the vector. If there are no nonzero elements, a value of 1 is returned. As of now, I have a working program that calculates the correct answer, however it computes the product of all elements, instead of all nonzero elements. I am asking for help on how to make this simple change in my program. Below is what I have so far.

function prod = ex1(v)
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vLength = length(v);
prod = 1;
CurrentPosition = 1;

for CurrentPosition = 1:vLength
    prod = prod * v(CurrentPosition);
    CurrentPosition = CurrentPosition + 1;
end

[Walter Roberson]

By the way, the code can be vectorized to less than 20 characters (excluding the "function" line.)

Answer 1

[James Tursa]

You need to wrap this statement with an if-test and only execute it if v(CurrentPosition) is non-zero:

prod = prod * v(CurrentPosition);

Also, get rid of the following line. You should not be manually altering the for-loop index variable within the loop:

CurrentPosition = CurrentPosition + 1;

You can get rid of this line also, since it doesn't actually accomplish anything useful.

CurrentPosition = 1;