Thursday, October 19, 2006

Unsolicited Letter to Microsoft

Dear Microsoft,
Please update the next version of Excel to include a portfolio variance and portfolio sigma function. Otherwise, we poor users have to resort to equations like this for a mere 6-asset optimization: =((AK18^2*$Q$5+ AK19^2*$R$6+ AK20^2*$S$7+ AK21^2*$T$8+ AK22^2*$U$9+ AK23^2*$V$10)+ (2*AK18*AK19*$Q$6+ 2*AK18*AK20*$Q$7+ 2*AK18*AK21*$Q$8+ 2*AK18*AK22*$Q$9+ 2*AK18*AK23*$Q$10+ 2*AK19*AK20*$R$7+ 2*AK19*AK21*$R$8+ 2*AK19*AK22*$R$9+ 2*AK19*AK23*$R$10+ 2*AK20*AK21*$S$8+ 2*AK20*AK22*$S$9+ 2*AK20*AK23*$S$10+ 2*AK21*AK22*$T$9+ 2*AK21*AK23*$T$10+ 2*AK22*AK23*$U$10))
If we call the new function "portvar," then the whole equation is simply: =portvar(I4:N142), and that is much more efficient.

1 comment:

Anonymous said...

You do know that you can create your own user-defined functions within Excel's using Visual Basic for Applications, right?