<prompt> Human: I currently have the expected returns, the standard deviations, and the correlation matrix for 46 asset classes.How do I get to the portfolio variance? I was reading online that I need to come up with a covariance matrix. Is this similar to the correlation matrix?Thanks a ton!  <response>: How to make the variance-covariance matrix in Excel:The narrator explains the process step by step and then at the very end shows how you can do it all in one step. It probably pays to duplicate his step by step work so you see where things are coming from.Make sure to use Control-Shift-Enter to get formulas to apply across the entire matrix cell range all at once. 