Wrong results using the SUM in XPATH- Edit data

Question

I have a problem when try to do a sum operation using the XPATH function on a set of decimal values:
To explain it simple, a Service script(also have tried in BPA) which has a edit data step as below
move '2108.39' to "parm/+listofpay/amt";
move '1330.8' to "parm/+listofpay/amt";
move '189.83' to "parm/+listofpay/amt";
move '4561.12' to "parm/+listofpay/amt";
move '480.55' to "parm/+listofpay/amt";
move "sum(parm/listofpay/amt)" to "parm/totamt";
and the schema is
<schema>
<totamt dataType="number"/>
<listofpay type="list">
<amt dataType="number"/>
</listofpay>
</schema>
When tried to display(calling through a BPA) the parm/totamt i get a result 8670.68999999999 instead of 8670.69
Oracle support says it a problem with rounding, how can we have a rounding problem in addition ?
any suggestions please ?

Answer 1

Hi Manfred!
Our setup is very straight forward. We are using a generic M-Series board to generate the stimulus signal as follows:
Output frequency for x-number of cycles - measure gain/phase response.
To sample the response, we are using an S-Series board. All of it is done using DAQmx drivers, which again, I don't think makes any difference, since we are experiencing the same problems with a 'pure' software simulation.
Our unit under test is comprised of a resistor and a capacitor, which represents a simple low pass filter with predictable gain/phase response.
It appears to us that the erratic phase response at higher frequencies is a result of 1pi versus 2pi phase wrap or flip, which may not be handled correctly by the lock-in tool kit.
We were thinking of "unwrapping" the phase, but I wanted to find an explanation for this behaviour first, to ensure that we are not dealing with a software bug.
Also, where can we find the unwrap phase.vi?
Thanks,
Markus
www.movimed.com - Custom Imaging Solutions
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