Creating formulas in analytical reports?

Hi,

I'm trying to create additional columns to an analytical report on Contract Workspace Procurement.(CWS)

I would like to know if the CWS effective date is less than 90 days old.

I can select the Contract Workspace Procurement Fact. Go to custom formula and then I need to enter the formula, but what should I type?

I've tried something like this:

sum(if(now().day-EffectiveDate.day<90)Count(ContractWorkspace))

I've search the online documentation but I haven't been able to find anything on the syntax to use.

I have found the report_field_dictionary.xls so the effective date is called EffectiveDate, so far so good, but how do I get the variable "now" or "today"?

And what is the right syntax to use when writing custom formulas?

Br

Chr