Saving output into different xls workbooks

Hi, I am running linprog that contains 3 variables changing according to 'for' loops. Let's call the 3 variables 'aa','bb','cc'. I am getting my outputs in the form of matrix 'OUTPUT(aa,bb)', which is what I want. Now, I want to save the output for each value of 'cc' into an excel workbook, with each sheet called "optimization.cc" which will contain the (aa,bb) matrix for that particular value of 'cc'.

Also, I want to make graphs from the outputs. Should I save it as a .csv or .xls? I want to minimize the processing time.

Thank you!