Calculations based on Summarized data in Cross Tab

Question

First off, I'm pretty experienced with Crystal.
I've run accross something that seems like it should be realy easy to do, and the sort of thing you would expect to do  in a cross tab... so maybe I'm missing something totally obvious.
I'm doing a year over year comparison of some financial data broken down by month and by quarter.
So, my Rows are Quarter, and a field called 'YEARMONTH' (calculated field, YYYYMM, for ease of sorting)
My column is Year, and for summarized fields, I have the data field I'm interested in which is a float. Let's call it 'Dollars' for sake of argument.
What I want to do is create a summary field (next to the total field) called 'Difference' or 'Delta' that calculates for reach row the difference between my two years (2008, and 2009)
The only solution I can come up with is to dummy in a record from the datasource with a year value of 'Difference' and some other dummy values so that it will show up as a column on the cross tab, and then somehow use the currentrowcolum function or some such creature to mask the output in the column. but now that I type it out here, I'm not sure it's going to work. I also don't think it's going to export the way I want it to either.
I'd really prefer it to be in a cross tab, and not in some manually created cross-tab emulation using manual running totals, but I'll go there if I have to.
Thanks a ton!

Answer 1

This is what I did in my report to get the difference
my crosstab looks like this
                    2004     2005    Total
Total              T1         T2         T
USA               A          B          C
INDIA              X          Y          Z
right click on T1 and go to format field and write the suppress condition like this
numberVar d:=0;
currencyVar array arr1;
currencyVar array arr2;
numberVar e;
if GridRowColumnValue('year')=2004 then
(e:=e+1;
redim preserve arr1[e];
arr1[e]:=CurrentFieldValue)
else
(e:=e+1;
redim preserve arr2[e];
arr2[e]:=CurrentFieldValue);
false
right click on T and go to format field and write the Display string condition like this
currencyVar array arr1;
currencyVar array arr2;
totext(arr1[1]-arr2[1])
right click on A and go to format field and write the suppress condition like this
currencyVar array four;
currencyVar array five;
numberVar d;
if GridRowColumnValue('year')=2004 then
(d:=d+1;
redim preserve four[d];
four[d]:=CurrentFieldValue)
else
(d:=d+1;
redim preserve five[d];
five[d]:=CurrentFieldValue);
false
right click on C and go to format field and write the Display string condition like this
currencyVar array four;
currencyVar array five;
numberVar g;
g:=g+1;
ToText(four[g]-five[g])
Note: Please select the option "column totals on top" for crosstab in customize style
Hope this helps!
Raghavendra