you need a calculation field:
RunningTotalField + StartNumberField
Stephen Huston: I think you misunderstood my msg above, or likely I don't understand your response. How can I use a plus-sign to achieve a subtraction?
To clarify my intent: Assume my Annuity at end Dec '16 was $100,000. The field is (n_start value)
Then, each month I receive a payment of $1000 (n_gross_pay) less Fed tax (n_fed_tax), less State tax (n_state_tax) equals (c_amt_rec'd). Assume this value is $600 and is subtracted from my annuity balance each month.
The latter is a Calculation field: c_amt.rec'd) Calculation =Sum ( n_gross; -n_fed.tax; - n_st.tax ); Assume $600.
Then I have a field n_annuity_balance, which I want to be a running-balance of the value of the annuity, e.g.:
Jan 31: $99,400; Feb 28: $98,800; Mar 31: $98,200; etc.
Using the Starting Balance then a Summary field (or other method) to subtract the result of c_amt_rec'd each month.
I hope this isn't too confusing;
Set up your running total summary field to total the c_amt_rec'd field.
Then use the summary field in the calculation that Stephen has suggested and put the calculation field on your layout in place of the summary field. StartNumber field can be a field from a related table, global field or global variable.
Voila! I finally got it!! Thank you Stephen Huston & philmodunk. Phil, this is the 2nd time you've helped. You showed me how to apply Stephen's response.
However, I've had to modify it as follows; StartNumberField — RunningTotalField:
c_start_minus_run Calculation Unstored, = n_start_value - s_running_total.
You've taught me how Functions can used within other Functions. Thanks!!