' Cumulative standard deviation

TYPE Sample
  N AS INTEGER
  Sum AS SINGLE
  SumOfSquares AS SINGLE
END TYPE

DECLARE SUB Init (S AS Sample)
DECLARE SUB Add (S AS Sample, BYVAL P AS SINGLE)
DECLARE FUNCTION Deviation! (S AS Sample)
DIM Test(1 TO 8) AS SINGLE
DIM S AS Sample
FOR I = 1 TO 8
  READ Test(I)
NEXT I
DATA 2, 4, 4, 4, 5, 5, 7, 9
CALL Init(S)
PRINT "N ITEM AVG   STDDEV"
FOR I = LBOUND(Test) TO UBOUND(Test)
  CALL Add(S, Test(I))
  PRINT USING "# "; I;
  PRINT USING "   # "; Test(I);
  PRINT USING "#.### "; S.Sum / I;
  PRINT USING " #.###"; Deviation!(S)
NEXT I
END

SUB Add (S AS Sample, BYVAL P AS SINGLE)
  S.N = S.N + 1
  S.Sum = S.Sum + P
  S.SumOfSquares = S.SumOfSquares + P ^ 2
END SUB

FUNCTION Deviation! (S AS Sample)
  Deviation! = SQR(S.SumOfSquares / S.N - (S.Sum / S.N) ^ 2)
END FUNCTION

SUB Init (S AS Sample)
  S.N = 0
  S.Sum = 0!
  S.SumOfSquares = 0!
END SUB