dim SD.storage$( 100)   '   can call up to 100 versions, using ID to identify.. arrays are global.
                            '   holds (space-separated) number of data items so far, current sum.of.values and current sum.of.squares

    for i =1 to 8
        read x
        print "New data "; x; " so S.D. now = "; using( "###.######", standard.deviation( 1, x))
    next i

    end

function standard.deviation( ID, in)
  if SD.storage$( ID) ="" then SD.storage$( ID) ="0 0 0"
  num.so.far =val( word$( SD.storage$( ID), 1))
  sum.vals   =val( word$( SD.storage$( ID), 2))
  sum.sqs    =val( word$( SD.storage$( ID), 3))
  num.so.far =num.so.far +1
  sum.vals   =sum.vals   +in
  sum.sqs    =sum.sqs    +in^2

  ' standard deviation = square root of (the average of the squares less the square of the average)
  standard.deviation   =(               ( sum.sqs /num.so.far)      -    ( sum.vals /num.so.far)^2)^0.5

  SD.storage$( ID) =str$( num.so.far) +" " +str$( sum.vals) +" " +str$( sum.sqs)
end function

    Data 2, 4, 4, 4, 5, 5, 7, 9