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#1
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Prime Numbers?
Hello,
I am looking for a function that will return a prime number in Excel. Is there such a thing? Is it possible to obtain prime numbers in a simple and easy way? Keith |
#2
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Prime Numbers?
Hi Keith
=3 <vbg but I don't thinks this is what you want. what are you trying to achieve (generating prime numbers within a range, getting the largest prime within a range, sieving primes, etc?). You may have a look at http://www.utm.edu/research/primes/ Frank Keith wrote: Hello, I am looking for a function that will return a prime number in Excel. Is there such a thing? Is it possible to obtain prime numbers in a simple and easy way? Keith |
#3
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Prime Numbers?
Keith,
Here is a routine originally presented by Myrna Larson that I use to test for primes. =IsPrime(num) returns True or False. Function IsPrime(TestNum As Long) Dim PrimeCnt As Long Dim y As Long Dim x As Long Dim i As Long Dim Flag As Boolean Dim Primes() As Long Dim NumStop As Double ReDim Primes(1 To 2) NumStop = Sqr(TestNum) If TestNum = 1 Or TestNum = 2 Or TestNum = 3 Or TestNum = 5 Then IsPrime = True Exit Function End If Primes(1) = 2 Primes(2) = 3 PrimeCnt = 2 x = 3 Do x = x + 2 For y = 3 To Sqr(x) Step 2 If x Mod y = 0 Then GoTo NoPrime1 Next y PrimeCnt = PrimeCnt + 1 ReDim Preserve Primes(1 To PrimeCnt) Primes(PrimeCnt) = x NoPrime1: Loop Until Primes(PrimeCnt) NumStop For i = LBound(Primes) To UBound(Primes) If TestNum Mod Primes(i) = 0 Then IsPrime = False Exit Function End If Next IsPrime = True End Function -- HTH Bob Phillips ... looking out across Poole Harbour to the Purbecks (remove nothere from the email address if mailing direct) "Keith" wrote in message ... Hello, I am looking for a function that will return a prime number in Excel. Is there such a thing? Is it possible to obtain prime numbers in a simple and easy way? Keith |
#4
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Prime Numbers?
Hi Keith,
If you do a search on Internet you will find lists of prime numbers and agorithms to create such a list. What exactly do you require? Just one prome numer or a function that takes a prime number randomly from a list? -- Kind Regards, Niek Otten Microsoft MVP - Excel "Keith" wrote in message ... Hello, I am looking for a function that will return a prime number in Excel. Is there such a thing? Is it possible to obtain prime numbers in a simple and easy way? Keith |
#5
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Prime Numbers?
"Keith" wrote in message ... Hello, I am looking for a function that will return a prime number in Excel. Is there such a thing? Is it possible to obtain prime numbers in a simple and easy way? Keith see the code at the bottom of this page http://members.chello.nl/n.sterk/Exc...xcel_files.htm Keith Willshaw |
#6
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Prime Numbers?
Thank you to all who replied.
I actually am attempting to generate a list of primes, so the routine that tests for primes will work, and I'll also look at the other suggestions. thanks very much, keith |
#7
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Prime Numbers?
Keith wrote:
Thank you to all who replied. I actually am attempting to generate a list of primes, so the routine that tests for primes will work, and I'll also look at the other suggestions. thanks very much, keith Hi Keith I would suggest to import an existing list of primes. e.g. http://www.utm.edu/research/primes/lists/small/1000.txt Frank |
#8
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Prime Numbers?
Here's another new suggestion:
I do not quite know if this software can contribute, but i just wanted to let you know, that we developed a collection of functions (library, dll) for working with real big numbers. (...numbers bigger than the normal data types a programmer can handle.) It was made for Visual Basic, but can be used in any language that can invoke a .DLL (such as C++, VBA in Excel, Access or whatever) It's the only DLL available for Windows for UNLIMITED BIG NUMBERS with functions such as: +/-* Power2, Power10, MOD DIVIDE, ISPRIME, COMPARE, Xor etc... Calculations are sometimes even faster than you are used to, cause everything was made in assembly. It's shareware and it is online on http://www.big-numbers.com David "Frank Kabel" schreef in bericht ... Keith wrote: Thank you to all who replied. I actually am attempting to generate a list of primes, so the routine that tests for primes will work, and I'll also look at the other suggestions. thanks very much, keith Hi Keith I would suggest to import an existing list of primes. e.g. http://www.utm.edu/research/primes/lists/small/1000.txt Frank |
#9
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Prime Numbers?
Where can I get the function
=IsPrime(num I typed it in a cell and got an error message Is there an add-on for more functions in Excel I want an IF test for a cel =IF(IsPrime(B1),"Prime","Composite") |
#10
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Prime Numbers?
Hi Nia,
Here is a routine originally presented by Myrna Larson that I use to test for primes. =IsPrime(num) returns True or False. Function IsPrime(TestNum As Long) Dim PrimeCnt As Long Dim y As Long Dim x As Long Dim i As Long Dim Flag As Boolean Dim Primes() As Long Dim NumStop As Double ReDim Primes(1 To 2) NumStop = Sqr(TestNum) If TestNum = 1 Or TestNum = 2 Or TestNum = 3 Or TestNum = 5 Then IsPrime = True Exit Function End If Primes(1) = 2 Primes(2) = 3 PrimeCnt = 2 x = 3 Do x = x + 2 For y = 3 To Sqr(x) Step 2 If x Mod y = 0 Then GoTo NoPrime1 Next y PrimeCnt = PrimeCnt + 1 ReDim Preserve Primes(1 To PrimeCnt) Primes(PrimeCnt) = x NoPrime1: Loop Until Primes(PrimeCnt) NumStop For i = LBound(Primes) To UBound(Primes) If TestNum Mod Primes(i) = 0 Then IsPrime = False Exit Function End If Next IsPrime = True End Function -- HTH Bob Phillips ... looking out across Poole Harbour to the Purbecks (remove nothere from the email address if mailing direct) "Nia" wrote in message ... Where can I get the function? =IsPrime(num) I typed it in a cell and got an error message. Is there an add-on for more functions in Excel? I want an IF test for a cell =IF(IsPrime(B1),"Prime","Composite") |
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