[RESOLVED] Calculate 'Maximum' value

[Doogle]

I'm playing around with a 'general purpose' plotting routine. I have about 20 different sets of data, each with it's own maximum possible value. The data is added to every 2 weeks.

For instance, one set could range from 0 to 600 whilst another could be 0 to 20.

What I would like to do is find the maximum value in a given set and then round it up to, say, in the case of the 0 to 600 series, the nearest 50/100. So if the largest value in week n is 575 I'd like to round it to 600. in the case of a series from 0 to 20, if the largest value is 15.5 I'd like to round it up to 20.

The rounded value will be used to set the maximum Y value on the chart.

I can think of a method, involving repeatedly diving by 10 to find the magnitude but was wondering if anyone has a more elegant solution.

The language is fairly unimportant, although a 'basic' type would be helpful. The implementation will be in Mobile Basic for iPad.

[Doogle]

Thought it may help if you saw a screen shot. Looking at the Platelets plot the largest value is 552 and I would like then 'ymax' to be 600. I also will need to annotate the y axis with appropriate values. The largest Neuts is 11.4 and I would like to sent 'ymax' to 20 on that graph.

[dclamp]

Since I know PHP best, I wrote the following code in PHP. The theory could easily be implemented in any language.

$number = 65;

if ($number < 100) {
     $round = 10;
} elseif ($number > 100 && $number < 1000) {
     $round = 100;
} elseif ($number > 1000 && $number < 10000) {
     $round = 1000;
}

echo ceil($number/ $round) * $round; 

You can see it in action here... Change the Number variable to see different numbers.
http://sandbox.onlinephpfunctions.co...fa06866fac6cf2

[Nightwalker83]

I had a go at converting the php code into VB.NET.

Public Class Form1
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim number As Integer, round As Integer
        number = 100
        If number < 100 Then
            round = 10
        ElseIf number >= 100 & number < 1000 Then
            round = 100
        ElseIf number >= 1000 & number <= 10000 Then
            round = 1000
        End If
        MessageBox.Show(Math.Ceiling(number / round) * round)
    End Sub
End Class

[dclamp]

Addition to the above code. It should be greater than equal to and lessthan equal to... I got errors if the number was 100, 1000, etc

[Nightwalker83]

Addition to the above code. It should be greater than equal to and lessthan equal to... I got errors if the number was 100, 1000, etc

Ah ok thanks! That is what I had originally but deleted it since you didn't have it in your code.

[dclamp]

Ah ok thanks! That is what I had originally but deleted it since you didn't have it in your code.

Yeah I didnt update the code, But updated in the sandbox thing I was playing with. Also, on the last condition you have <= 1000, should be 10000

[Nightwalker83]

Yeah I didnt update the code, But updated in the sandbox thing I was playing with. Also, on the last condition you have <= 1000, should be 10000

Fixed!

     ElseIf number >= 1000 & number <= 10000 Then

Edit:

I originally tried to convert it to VB6 but none of codes for ceil (that I found) worked correctly.

[dilettante]

How about something like (VB6):

Private Sub FindScaleMax()
    Dim OrderMag As Single
    Dim Mag As Single

    OrderMag = Int(Log(Largest) / Log(10)) 'Integer part of Log10(Largest).

    Mag = 10 ^ OrderMag

    ScaleMax = (Int(Largest / Mag) + 1#) * Mag
End Sub

[Doogle]

Perfect. Thanks Dilettante.

[dilettante]

I was a little surprised you didn't get an answer earlier.

This is an example of a class of small problems often used for the performance section of programming job interviews in scientific and engineering companies. They send you to the whiteboard to watch you solve a few such problems. Even if the problem isn't completed, and it generally isn't, attempted solutions using logarithms are "pass" and anything based on iteration is a "fail."

Some say this skews in favor of "conventionality" while the defenders says it evaluates problem solving skills.

[Doogle]

I might have come up with the Log solution given enough time. The next interesting problem is using the scale max to create tick marks and labels for the y-axis. When I get stuck no doubt I'll be posting here again.