Average value in variable array?

lardom

What is the syntax in Spin for calculating the average value in a variable array? (If you can only add one element at a time a block of code could get really large).

JonnyMac

Is this a trick question or am I missing something?

pub average(p_array, elements) | acc

  acc := 0                                                      ' clear accumulator

  repeat elements                                               ' total all
    acc += long[p_array]                                        ' get one
    p_array += 4                                                ' point to next element

  return acc / elements                                         ' return average

If memory serves me, Phil (PhiPi) had some code to do a running average posted a while back -- you might want to do a search for that.

Mike Green

You use a loop to add all the elements into a temporary variable, then divide by the number of elements like

var long average, i, array[ n ]
' ...
average := 0
repeat i from 0 to n-1
   average += array[ i ]
average /= n

lardom

@JonnyMac, it's not a trick question. Thanks for the compliment and the code. I was just studying the "PUB Average" method of an 'ADC' object because what I was thinking would have filled two pages.
@Mike Green, Thanks.

lardom

Mike and JonnyMac, thanks again. I haven't tested this but the logic makes sense to me. I'm working on a 'bi-parented, child controlled autonomous navigation robot'. This piece of code has to find the widest path with a servo/ping combination that scans 180° in 20° increments.

VAR
    long AveDistance[6], PingDistance[9], Wide_Path, Rotate_Amount

PUB Find_Corridor  | i, j   

    i:= 0
    repeat j from 1 to 6
      repeat 4
        AveDistance[j]+= PingDistance[i]
        i++
      AveDistance[j]/= 4
      i-= 2
   
    repeat j from 1 to 6                    
      if AveDistance[j] > Wide_Path
        Wide_Path := AveDistance[j]
        Rotate_Amount := j