Exponential averaging function in MS 8.1?

[p15218]

Hi. I'm looking for an array exponential averaging function in MS 8.1 enterprise and it looks to me like nothing exists.

I need to have a "running" average of autospectrum data. I've built a function that uses a collection to do a simple running average but an exponential running average would be prefered.

thanks

Bob

[EadieU]

Hi Bob,

Your searching is correct; there is not an exponential moving average function in Measurement Studio.  Here's some example C-code for an exponential average (aka, exponentially weighted average). You'll need to modify it a little to get it to be a moving average, but hopefully this will get you started: 

#include <ansi_c.h>

int main (int argc, char *argv[])
{
   double data[20] = {99, 50, 24, 50, 22, 48, 89, 10, 8, 45, 22, 6, 99, 99, 99, 99, 99, 99, 99, 99};
   double ex_data[20];
   int i;
   double multiplier, sum = 0.0, ex_avg = 0;
   int size = sizeof(data)/sizeof(data[0]);
   double f = 1.0 - 2.0/(20.0/2.8854);

   for (i = 0; i < size; i++) {
      multiplier = (1 - f) * pow(f,i);
      sum += multiplier;
      ex_avg += data[i] * multiplier;
      ex_data[i] = data[i] * multiplier;
   }

   printf ("sum (Should approach 1) = %f\naverage = %f", sum, ex_avg); 

   getchar ();
   return 0;
}