ph_runavg PowerHome formula function
Description
Performs a running average calculation on the
supplied data
Syntax
ph_runavg ( ad_avg, ad_newdata, al_samplecnt )
| Argument | Description |
| ad_avg | Double. The current running average value from
previous executions of this function. If this is the first
sample for the running average, set this value the same as ad_newdata so the returned
result won't be skewed |
| ad_newdata | Double. This is the new value to be figured
into the running average |
| al_samplecnt | Long. This is the number of samples to keep in
the running average. You should use a value > 1 otherwise the function will do nothing other than to return the
supplied ad_newdata value |
Return value
Double. Returns the running average
based upon
the supplied parameters
Usage
Use this formula to perform running averages
on values. Very useful for averaging data such as temperatures over
multiple samples to smooth false readings. This is the same function that is
used by the Analog I/O screens running
average column.
This function uses the following formula to calculate a running average:
If the al_samplecnt parameter is < 1,
then the return value will be ad_newdata. Any other sample count value will
result in returning a value based upon the following formula: ad_avg - ad_avg /
al_samplecnt + ad_newdata / al_samplecnt<
/p >
Examples
The following examples demonstrate typical syntax/usage for this function.
• ph_runavg(75.0,76.3,5) - Returns a
value of 75.26. The ad_avg value of 75.0 is the current running
average. The ad_newdata value is the new value to be calculated into the
running average. The al_samplecnt value of 5 signifies that the running
average is calculated over the last 5
samples