Question Array + Function + GOD BLESS AMERICA

[sosarya]

Hello all!
I am currently trying to write a program for my class.

The program's purpose is to find standard deviation of a group of numbers.

I managed to write the whole the program without using any functions but the instructor wants to see function in this program. This is where I need help.

Here is my program.

Dim a,sum,sserror,fvar,dSD As Decimal
Integer.Tryparse(Inputbox("Enter number"),a)
a = int(Rnd()*100)

Dim array(a-1) As Integer

For i=0 to a-1
array(i) = 5
Next

For j=0 to a-1
sum = sum + array(j)
Next

avg= sum/a

For k=0 to a-1
sserror = sserror + (array(k) - avg)*2
Next

dVar= sse / a 'calculates variance
dSD = dVar / 2 ' calculates st.deviation

The whole calculation code should be done in function part of the program and it should just call the function to textbox.
The output is the standard deviation of random numbers. It should be shown in textbox1.text

Instructor wants us to make this output by using the code textbox1.text = stdevFUNCTION(array)

I really appreciate any help

MAY THE FORCE BE WITH YOU

EVEN IF YOU DON'T LIKE STAR WARS

[Niya]

Well here is one way: You could place the part that creates that first array inside a function:-

'
    Private Function CreateArray(ByVal count As Integer) As Integer()
        Dim arr As Integer() = New Integer(count - 1) {}
        For i = 0 To count - 1
            arr(i) = 5
        Next
        Return arr
    End Function

And change your code to:-

'
        Dim a, sum, sserror, fvar, dSD As Decimal
        Integer.TryParse(InputBox("Enter number"), a)
        a = Int(Rnd() * 100)
 
        Dim array As Integer() = CreateArray(a)
 
        For j = 0 To a - 1
            sum = sum + array(j)
        Next
 
        avg = sum / a
 
        For k = 0 To a - 1
            sserror = sserror + (array(k) - avg) * 2
        Next
 
        dVar = sse / a 'calculates variance
        dSD = dVar / 2 ' calculates st.deviation

[sosarya]

Hello Niya thanks for your answer.

I need to ask,

How and which part of the code should I call the function, into the textbox?

I tried textbox1.text = createarray(array) but it is not working

Sorry I am a total newbie in functions..

[Niya]

I already changed your code to call CreateArray. Its on line 6:-

Dim array As Integer() = CreateArray(a)

[sosarya]

It had to be coded like this textbox1.text = stdevFUNCTION(array) because the instructor wants like this way

st.deviation result is our output which should appear in textbox1.text

I am confused

[Niya]

Oh, I misunderstood the question. To be honest, I don't know what a deviation is so I wouldn't know how to pick apart your code to put only the relevant parts into a function but I can point you to resources that explain how functions work and you can put the necessary parts into a function yourself. Here is one resource.

[sosarya]

st.dev is just a simple formula that's already in the code

dVar = sse / a 'calculates variance
dSD = dVar / 2 ' calculates st.deviation

dSD is where the answer lies

[dunfiddlin]

I'm sorry but in what sense have you "managed to write the whole the program"? With Option Strict Off, I get 5 errors in the code. With Option Strict On, it likes up like a Christmas tree! And as far as I can see (without correcting all those errors and actually trying it because life, frankly, is too short), the final calculation will always return 0 (if anything at all). It's nonsense from beginning to end.

[Niya]

st.dev is just a simple formula that's already in the code

If so then:-

'
    Private Function CalculateDeviation(ByVal sse As Decimal, ByVal a As Decimal) As Decimal
        Dim dVar As Decimal
        dVar = sse / a 'calculates variance
        Return dVar / 2 ' calculates st.deviation
    End Function

[dunfiddlin]

Option Strict On
 
Public Class Form1
    Dim r As New Random
    Private Sub Form1_Load(sender As Object, e As System.EventArgs) Handles Me.Load
        Dim test(7) As Decimal ' set up a test array of
        For i = 0 To 7
            test(i) = r.Next(11) ' random values 0 to 10
        Next
        Me.Text = StandardDeviation(test).ToString ' function
    End Sub
 
    Function StandardDeviation(ByVal values() As Decimal) As Decimal
        Dim Mean As Decimal = values.Sum / values.Length ' get average of all array values
        Dim Diff As Decimal
        For Each d In values
            Diff = CDec(Diff + ((d - Mean) ^ 2)) ' calculate difference squares & sum them
        Next
        Return CDec(Math.Sqrt(Diff / values.Length)) ' return deviation
    End Function
End Class

[sosarya]

Hello! I want to add something to this code.

I want to add a inputbox which asks for number count.

For example if you enter 5, then you have 5 random numbers..

Option Strict On
 
Public Class Form1
    Dim r As New Random
    Private Sub Form1_Load(sender As Object, e As System.EventArgs) Handles Me.Load
        Dim test(7) As Decimal ' set up a test array of
        For i = 0 To 7
            test(i) = r.Next(11) ' random values 0 to 10
        Next
        Me.Text = StandardDeviation(test).ToString ' function
    End Sub
 
    Function StandardDeviation(ByVal values() As Decimal) As Decimal
        Dim Mean As Decimal = values.Sum / values.Length ' get average of all array values
        Dim Diff As Decimal
        For Each d In values
            Diff = CDec(Diff + ((d - Mean) ^ 2)) ' calculate difference squares & sum them
        Next
        Return CDec(Math.Sqrt(Diff / values.Length)) ' return deviation
    End Function
End Class

[dunfiddlin]

So ...

Private Sub Form1_Load(sender As Object, e As System.EventArgs) Handles Me.Load
inputbox goes here and value gets used as array size on the next line
Dim test(7) As Decimal ' set up a test array of

... you should be able to do that without too much problem.

[sosarya]

Okay i got it

you are the man

i am the dog