Searching for a suitable algorithm

General
1

Hello,

I’ve got something to analyze today. Given is a value “MyValue”, on the basis of which a value “Difference” should be calculated.
Does anyone recognize a pattern, an algorithm, from my manual Select…Case…query? What could this algorithm look like without having to specify a single case for all areas?

[code]Select Case MyValue
Case 3
Difference = 0.5
Case 4
Difference = 0.75

// Following results: Steps 2
Case 5 To 6
Difference = 1
Case 7 To 8
Difference = 1.25

// Following results: Steps 5
Case 9 To 13
Difference = 2
Case 14 To 18
Difference = 3
Case 19 To 23
Difference = 4
Case 24 To 28
Difference = 5
Case 29 To 33
Difference = 6
Case 34 To 38
Difference = 7

// Following results: Steps 4
Case 39 To 42
Difference = 8
Case 43 To 46
Difference = 9
Case 47 To 50
Difference = 10
// And so on…
End Select[/code]

2

A large array of preset differences with an index myValue would find the difference in one step.

3

Dim diff() As Double = Array(0,0,0, 0.5, 0.75, 1, 1, 1.25, 1.25, 2, 2, 2, 2, 2, ...) Dim theDiff As Double = diff(MyValue)

4

Thanks Rick for your suggestion. I’ve reworked my code. So it returns the same results without having to create an extra case for each area.

[code]Dim diff, start As Double

Select Case MyValue
Case 3
diff = 0.5

Case 4 To 8
start = 0.5

For i As Integer = 5 To MyValue Step 2
start = start + 0.25
Next

diff = start + 0.25

Else
start = 3

For i As Integer = 9 To MyValue Step 5
start = start + 1
Next

diff = start - 2

End Select[/code]

5

Your first method returns 9, 10, 10 to MyValues 43,47,48. Your second slower method returns 8, 9, 9.

6

Yes, I’ve modified the different value factor. Is it much slower than the first method?

7

Yes. Higher MyValues = more iterations (loop).

You can translate your second effort as pure math as:

[code] Dim diff As Double
Dim delta As Integer

Select Case MyValue

Case Is < 3
diff = 0

Case 3
diff = 0.5

Case 4 To 8

delta = (MyValue-5)/2+1
diff = 0.75 + (delta * 0.25)

Case Is > 8

delta = (MyValue-9)/5+2
diff = delta

End Select

Return diff[/code]