How to calculation positive and negative subtotals?

[Rujie]

I need to sum all positive amounts and sum all negative
amounts. They should be also printed on each page of a
report header section. Can any one give me some ideas how
I should do this?
Thanks.

 

[Duane Hookom]

The expression for all positive values would be:
=Abs(Sum([Amount]>=0 * [Amount]))
Negative values
=Sum([Amount]<0 * [Amount])
I'm not sure what you mean by "each page of a report header section."