Twin Primes

This code has been declared by its author to be Public Domain code.

Twin Primes by daaan

2006

I had a assembly programming assignment that was to print out the first 100 twin primes. So I made this mock up program to figure how a easy method for calculating twin primes. It does in fact work, but now I need to translate it into assembly :(

Rem
**********************************************************
twin primes by daniel wooden
**********************************************************
End Rem

Local count:Int = 1
Local curnum:Int = 3

Local a:Int = 0
Local b:Int = 0

While count < 101 ' <-- twin primes upto the 100th place.
	
	If IsPrime( curnum ) And IsPrime( curnum+2 ) Then
		a = curnum
		b = curnum+2
		Print "Twin Prime Set: " + count + " (" + a + "," + b + ")"
		count :+ 1
	End If
	
	curnum :+ 1
	
Wend
End

Function IsPrime:Int( Num:Int )
	
	Local Prime:Int = True
	
	For i = 2 To Num/2
		If (Num Mod i) = 0 Then
			Prime = False
		End If
	Next
	
	Return Prime
	
End Function

Comments

rdodson41

2007

Your calculating the even numbers too, try curnum :+ 2, should go twice as fast.

Azathoth

2007

To make IsPrime faster you should use 'Exit' after 'Prime = False' because you're still in the 'For-Next' loop when using large numbers.

ShadowTurtle

2007

compatible without blitzmax:

;**********************************************************
;twin primes by daniel wooden
;converted by shadowturtle
;**********************************************************


Local count = 1
Local curnum = 3

Local a = 0
Local b = 0

While count < 101
	
	If IsPrime( curnum ) And IsPrime( curnum+2 ) Then
		a = curnum
		b = curnum+2
		Print "Twin Prime Set: " + count + " (" + a + "," + b + ")"
		count = count + 1
	End If
	
	curnum = curnum + 1
	
Wend
WaitKey
End

Function IsPrime( Num )
	
	Local Prime = True
	
	For i = 2 To Num/2
		If (Num Mod i) = 0 Then
			Prime = False
		End If
	Next
	
	Return Prime
	
End Function

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