Re: More functions?

V5R4 added STDDEV_SAMP to STDDEV in SQL aggregate functions. Maybe one of these could be used, since a statement like

select stddev_samp(numfld)
into :hostvar
from somefile
where somefield = somevalue

Or use stddev_pop = whichever is the one he wants.

That'd be really easy inside RPG!!

HTH
Vern

Simon Coulter wrote:

On 16/02/2010, at 7:49 AM, James Newman, CDP wrote:

Anyone know a simple way to do this inside RPG?

STDDEV is a fairly simple calculation--although I think you're actually after a Sample Standard Deviation. Really just a sequence of addition, division, subtraction, squaring, addition, division, and square root--all of which can be done in RPG (even OPM RPG). Hardest part is keeping track of the stages but since you already know the limits (i.e., 60 values) arrays with that number of elements will suffice. Two arrays should do the trick: One array will hold the 60 original values, the other array will hold the calculated deviations from the mean, square them in place (i.e., same array), sum that array (XFOOT) and divide by one less than the number of elements, then calculate the square root of the final sum.

Load the array with the first 60 records and run the STDDEV calculation. As you process each new record (after the first 60) just shift up the elements in the first array, thus dropping the first element, and add the new element at the end. Then run through the STDDEV function again.

Is there a way to call a function in another language?

Yes, Use RPG IV, prototype the foreign function, and link to it at bind time. However, I'm not sure I see the relevance unless you hope to find a STDDEV function already written in another language.

Regards,
Simon Coulter.
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