"Collapse" function that calculates product

[Daria Fomenko]

Is there a function that does what the collapse function does but calculates the product of the values for the selected variable.

I need it to calculate the yearly return out of monthly returns.

Thank you very much in advance!

[Clyde Schechter]

If all of the values of the variable whose product you want are positive, you can collapse to the sum of its logarithm, and then exponentiate the sum.