Minimum time reqd. in calculation ??

**Morten Wennevik** · Nov 22 '05, 02:01 PM

Re: Minimum time reqd. in calculation ??

Hi A!,

There is no way we can tell you how to optimize your code when you don't show us the code :P
There is no way we can compare 15 ms to any of our own code either since you don't tell us what system you are running on.

--
Happy Coding!
Morten Wennevik [C# MVP]

**One Handed Man \( OHM - Terry Burns \)** · Nov 22 '05, 02:01 PM

Re: Minimum time reqd. in calculation ??

Post your code is a good start

--

OHM ( Terry Burns )
. . . One-Handed-Man . . .
If U Need My Email ,Ask Me

Time flies when you don't know what you're doing

"A!" <anonymous@disc ussions.microso ft.com> wrote in message
news:%23KhVVEim EHA.2500@TK2MSF TNGP09.phx.gbl. ..[color=blue]
> Hi all,
> I am writing an application in VB.NET to calculate the first 1000 prime
> numbers.
> The issue is the performance.... .I want the time taken to be minimum !
> I can achieve this in around 15 milliseconds now.
> Is there any way I can cut down this limit to less than a millisecond ?
> Please suggest.
> TIA.
>
>[/color]

A! · Nov 22 '05, 02:01 PM

Re: Minimum time reqd. in calculation ??

Thanks both of you.
Here's my code :
*************** **************

Imports System.Math

Private Sub Button3_Click(B yVal sender As System.Object, ByVal e As
System.EventArg s) Handles Button3.Click

Me.SuspendLayou t()

Dim i As Int16 = 3

Dim intCounter As Int16 = 2

Dim intDivider As Int16

Dim intRunner As Int16

Dim bolIsPrime As Boolean

Dim arrPrimes(999) As String

arrPrimes(0) = 2

arrPrimes(1) = 3

Dim sw As New StopWatch

Do While Not intCounter > 999

intDivider = Ceiling(Sqrt(i) )

If intDivider > 1 Then

For intRunner = 3 To intDivider Step 2

If (i Mod intRunner) = 0 Then

bolIsPrime = False

Exit For

End If

bolIsPrime = True

Next

If bolIsPrime Then

arrPrimes(intCo unter) = i

intCounter += 1

End If

End If

i += 2

Loop

'Comment these three lines out when measuring speed of the algo only

ListBox1.BeginU pdate()

ListBox1.Items. AddRange(arrPri mes)

ListBox1.EndUpd ate()

Label1.Text = (sw.Peek() / 10).ToString 'Time elapsed.

Me.ResumeLayout ()

End Sub

Private Sub Button1_Click(B yVal sender As System.Object, ByVal e As
System.EventArg s) Handles Button1.Click

ListBox1.Items. Clear()

End Sub

*************** **************

Also, I am running this on a P-4, 512 RAM, 40 GB HDD.

Thanks.

"One Handed Man ( OHM - Terry Burns )" <news.microsoft .com> wrote in message
news:%239QUjpim EHA.952@TK2MSFT NGP14.phx.gbl.. .[color=blue]
> Post your code is a good start
>
> --
>
> OHM ( Terry Burns )
> . . . One-Handed-Man . . .
> If U Need My Email ,Ask Me
>
> Time flies when you don't know what you're doing
>
> "A!" <anonymous@disc ussions.microso ft.com> wrote in message
> news:%23KhVVEim EHA.2500@TK2MSF TNGP09.phx.gbl. ..[color=green]
> > Hi all,
> > I am writing an application in VB.NET to calculate the first 1000 prime
> > numbers.
> > The issue is the performance.... .I want the time taken to be minimum !
> > I can achieve this in around 15 milliseconds now.
> > Is there any way I can cut down this limit to less than a millisecond ?
> > Please suggest.
> > TIA.
> >
> >[/color]
>
>[/color]

**Morten Wennevik** · Nov 22 '05, 02:01 PM

Re: Minimum time reqd. in calculation ??

Well, I tried translating your code to C# and I got 218ms (on a Celeron 1.7Ghz) when filling the ListBox and less than 100ns when not filling (ie too small a value for TimeSpan), so the time is spent on filling the ListBox, which I don't think you can speed up.

I had to make a couple of adjustments to your code, so it may not be correct. I also had to guess the contents of StopWatch, but it shouldn't affect speed.
Any C# people may want to try to optimize it (or spot errors in the translation).

public class Form1 : Form
{
public Form1()
{
InitializeCompo nent();
}

private void button1_Click(o bject sender, EventArgs e)
{
this.SuspendLay out();
short i = 3;
short intCounter = 2;
short intDivider;
short intRunner;
bool boolIsPrime = false;
object[] arrPrimes = new object[1000];
arrPrimes[0] = 2;
arrPrimes[1] = 3;

StopWatch sw = new StopWatch();

while(intCounte r < 1000)
{
intDivider = (short)Math.Cei ling(Math.Sqrt( i));
if(intDivider > 1)
{
for(intRunner = 3; intRunner <= intDivider; intRunner += 2)
{
if((i % intRunner) == 0)
{
boolIsPrime = false;
break;
}

boolIsPrime = true;
}

if(boolIsPrime)
{
arrPrimes[intCounter] = i;
intCounter++;
}
}

i += 2;
}

listBox1.BeginU pdate();
listBox1.Items. AddRange(arrPri mes);
listBox1.EndUpd ate();
label1.Text = sw.Peek().ToStr ing();
this.ResumeLayo ut();
}
}

class StopWatch
{
private DateTime start;
public StopWatch()
{
start = DateTime.Now;
}

public double Peek()
{
TimeSpan s = DateTime.Now - start;
return (double)(s.Tick s) / 10000;
}
}

--
Happy Coding!
Morten Wennevik [C# MVP]

**Niki Estner** · Nov 22 '05, 02:01 PM

Re: Minimum time reqd. in calculation ??

Google for "sieve of erathostenes". I think that should be a lot faster.

Niki

"A!" <anonymous@disc ussions.microso ft.com> wrote in
news:%23NmXVZjm EHA.3452@TK2MSF TNGP15.phx.gbl. ..[color=blue]
> Thanks both of you.
> Here's my code :
> *************** **************
>
> Imports System.Math
>
> Private Sub Button3_Click(B yVal sender As System.Object, ByVal e As
> System.EventArg s) Handles Button3.Click
>
> Me.SuspendLayou t()
>
> Dim i As Int16 = 3
>
> Dim intCounter As Int16 = 2
>
> Dim intDivider As Int16
>
> Dim intRunner As Int16
>
> Dim bolIsPrime As Boolean
>
> Dim arrPrimes(999) As String
>
> arrPrimes(0) = 2
>
> arrPrimes(1) = 3
>
> Dim sw As New StopWatch
>
>
> Do While Not intCounter > 999
>
> intDivider = Ceiling(Sqrt(i) )
>
> If intDivider > 1 Then
>
> For intRunner = 3 To intDivider Step 2
>
> If (i Mod intRunner) = 0 Then
>
> bolIsPrime = False
>
> Exit For
>
> End If
>
> bolIsPrime = True
>
> Next
>
> If bolIsPrime Then
>
> arrPrimes(intCo unter) = i
>
> intCounter += 1
>
> End If
>
> End If
>
> i += 2
>
> Loop
>
> 'Comment these three lines out when measuring speed of the algo only
>
> ListBox1.BeginU pdate()
>
> ListBox1.Items. AddRange(arrPri mes)
>
> ListBox1.EndUpd ate()
>
> Label1.Text = (sw.Peek() / 10).ToString 'Time elapsed.
>
> Me.ResumeLayout ()
>
> End Sub
>
>
>
>
> Private Sub Button1_Click(B yVal sender As System.Object, ByVal e As
> System.EventArg s) Handles Button1.Click
>
> ListBox1.Items. Clear()
>
> End Sub
>
> *************** **************
>
> Also, I am running this on a P-4, 512 RAM, 40 GB HDD.
>
> Thanks.
>
>
>
>
> "One Handed Man ( OHM - Terry Burns )" <news.microsoft .com> wrote in
> message
> news:%239QUjpim EHA.952@TK2MSFT NGP14.phx.gbl.. .[color=green]
>> Post your code is a good start
>>
>> --
>>
>> OHM ( Terry Burns )
>> . . . One-Handed-Man . . .
>> If U Need My Email ,Ask Me
>>
>> Time flies when you don't know what you're doing
>>
>> "A!" <anonymous@disc ussions.microso ft.com> wrote in message
>> news:%23KhVVEim EHA.2500@TK2MSF TNGP09.phx.gbl. ..[color=darkred]
>> > Hi all,
>> > I am writing an application in VB.NET to calculate the first 1000 prime
>> > numbers.
>> > The issue is the performance.... .I want the time taken to be minimum !
>> > I can achieve this in around 15 milliseconds now.
>> > Is there any way I can cut down this limit to less than a millisecond ?
>> > Please suggest.
>> > TIA.
>> >
>> >[/color]
>>
>>[/color]
>
>[/color]

**One Handed Man \( OHM - Terry Burns \)** · Nov 22 '05, 02:01 PM

Re: Minimum time reqd. in calculation ??

Whats StopWatch, is this your code ?, if so post it

--

OHM ( Terry Burns )
. . . One-Handed-Man . . .
If U Need My Email ,Ask Me

Time flies when you don't know what you're doing

"A!" <anonymous@disc ussions.microso ft.com> wrote in message
news:%23NmXVZjm EHA.3452@TK2MSF TNGP15.phx.gbl. ..[color=blue]
> Thanks both of you.
> Here's my code :
> *************** **************
>
> Imports System.Math
>
> Private Sub Button3_Click(B yVal sender As System.Object, ByVal e As
> System.EventArg s) Handles Button3.Click
>
> Me.SuspendLayou t()
>
> Dim i As Int16 = 3
>
> Dim intCounter As Int16 = 2
>
> Dim intDivider As Int16
>
> Dim intRunner As Int16
>
> Dim bolIsPrime As Boolean
>
> Dim arrPrimes(999) As String
>
> arrPrimes(0) = 2
>
> arrPrimes(1) = 3
>
> Dim sw As New StopWatch
>
>
> Do While Not intCounter > 999
>
> intDivider = Ceiling(Sqrt(i) )
>
> If intDivider > 1 Then
>
> For intRunner = 3 To intDivider Step 2
>
> If (i Mod intRunner) = 0 Then
>
> bolIsPrime = False
>
> Exit For
>
> End If
>
> bolIsPrime = True
>
> Next
>
> If bolIsPrime Then
>
> arrPrimes(intCo unter) = i
>
> intCounter += 1
>
> End If
>
> End If
>
> i += 2
>
> Loop
>
> 'Comment these three lines out when measuring speed of the algo only
>
> ListBox1.BeginU pdate()
>
> ListBox1.Items. AddRange(arrPri mes)
>
> ListBox1.EndUpd ate()
>
> Label1.Text = (sw.Peek() / 10).ToString 'Time elapsed.
>
> Me.ResumeLayout ()
>
> End Sub
>
>
>
>
> Private Sub Button1_Click(B yVal sender As System.Object, ByVal e As
> System.EventArg s) Handles Button1.Click
>
> ListBox1.Items. Clear()
>
> End Sub
>
> *************** **************
>
> Also, I am running this on a P-4, 512 RAM, 40 GB HDD.
>
> Thanks.
>
>
>
>
> "One Handed Man ( OHM - Terry Burns )" <news.microsoft .com> wrote in[/color]
message[color=blue]
> news:%239QUjpim EHA.952@TK2MSFT NGP14.phx.gbl.. .[color=green]
> > Post your code is a good start
> >
> > --
> >
> > OHM ( Terry Burns )
> > . . . One-Handed-Man . . .
> > If U Need My Email ,Ask Me
> >
> > Time flies when you don't know what you're doing
> >
> > "A!" <anonymous@disc ussions.microso ft.com> wrote in message
> > news:%23KhVVEim EHA.2500@TK2MSF TNGP09.phx.gbl. ..[color=darkred]
> > > Hi all,
> > > I am writing an application in VB.NET to calculate the first 1000[/color][/color][/color]
prime[color=blue][color=green][color=darkred]
> > > numbers.
> > > The issue is the performance.... .I want the time taken to be minimum !
> > > I can achieve this in around 15 milliseconds now.
> > > Is there any way I can cut down this limit to less than a millisecond[/color][/color][/color]
?[color=blue][color=green][color=darkred]
> > > Please suggest.
> > > TIA.
> > >
> > >[/color]
> >
> >[/color]
>
>[/color]