Module CheckIt {
      Function StdDev (A()) {
          \\ A()  has a copy of values
            N=Len(A())
            if N<1 then Error "Empty Array"
            M=Each(A())
            k=0
            \\ make sum, dev same type as A(k)
            sum=A(k)-A(k)
            dev=sum
            \\ find mean
            While M {
                  sum+=Array(M)
            }
            Mean=sum/N
            \\ make a pointet to A()
            P=A()
            \\ subtruct from each item
            P-=Mean

            M=Each(P)
            While M {
                  dev+=Array(M)*Array(M)
            }
            \\ as pointer to arrray
             =(if(dev>0->Sqrt(dev/N), 0), Mean)
      }
      Function randomNormal {
            \\ by default all numbers are double
            \\ cos() get degrees
          =1+Cos(360 * rnd) * Sqrt(-2 * Ln(rnd)) /2
      }
      \\ fill array calling  randomNormal() for each item
      Dim A(1000)<<randomNormal()
      \\ we can pass a pointer to array and place it to stack of values
      DisplayMeanAndStdDeviation(A())  ' mean ~ 1 std deviation ~0.5
      \\ check M2000 rnd only
      Dim B(1000)<<rnd
      DisplayMeanAndStdDeviation(B())  ' mean ~ 0.5 std deviation ~0.28


      DisplayMeanAndStdDeviation((0,0,14,14))  ' mean = 7 std deviation = 7
      DisplayMeanAndStdDeviation((0,6,8,14))  ' mean = 7 std deviation = 5
      DisplayMeanAndStdDeviation((6,6,8,8))  ' mean = 7 std deviation = 1

      Sub DisplayMeanAndStdDeviation(A)
            \\ push to stack all items of an array (need an array pointer)
            Push  ! StdDev(A)
            \\ read from strack two numbers
            Print "Mean is               "; Number
            Print "Standard Deviation is "; Number
      End Sub
}
Checkit