[bmx] Twin Primes by daaan [ 1+ years ago ]

[BlitzBot]

Title : Twin Primes
Author : daaan
Posted : 1+ years ago

Description : 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

Code :

Code: BlitzMax

1. Rem
2. **********************************************************
3. twin primes by daniel wooden
4. **********************************************************
5. End Rem
6.  
7. Local count:Int = 1
8. Local curnum:Int = 3
9.  
10. Local a:Int = 0
11. Local b:Int = 0
12.  
13. While count < 101 ' <-- twin primes upto the 100th place.
14.        
15.         If IsPrime( curnum ) And IsPrime( curnum+2 ) Then
16.                 a = curnum
17.                 b = curnum+2
18.                 Print "Twin Prime Set: " + count + " (" + a + "," + b + ")"
19.                 count :+ 1
20.         End If
21.        
22.         curnum :+ 1
23.        
24. Wend
25. End
26.  
27. Function IsPrime:Int( Num:Int )
28.        
29.         Local Prime:Int = True
30.        
31.         For i = 2 To Num/2
32.                 If (Num Mod i) = 0 Then
33.                         Prime = False
34.                 End If
35.         Next
36.        
37.         Return Prime
38.        
39. End Function

Comments :


rdodson41(Posted 1+ years ago)

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


Azathoth(Posted 1+ years ago)

 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(Posted 1+ years ago)

 compatible without blitzmax:

Code: [Select]

;**********************************************************
;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