I kept this prime number generator around for some time for instances concerning yet another prime number program:
It first uses the sieve to create the first 1024 primes into an array then uses that array to use a second sieve generator.
Fast it calculates the primes up to 1M in less than a second and 10M in 15 seconds. On a 64-bit AMD Hexacore at 3.90 Ghz
Also prompts to print or count primes. And prompts for upper limit for prime number. Displays runtime.
An example of a small prime generator:
It first uses the sieve to create the first 1024 primes into an array then uses that array to use a second sieve generator.
Fast it calculates the primes up to 1M in less than a second and 10M in 15 seconds. On a 64-bit AMD Hexacore at 3.90 Ghz
Also prompts to print or count primes. And prompts for upper limit for prime number. Displays runtime.
Code: (Select All)
Rem The Prime Number Generator v2.0a PD 2024.
Rem First release (06/06/2024)
Rem Release v2.0a (06/10/2024)
Rem Adds IsPrime to check test value.
DECLARE FUNCTION Keyboard$ ()
DECLARE FUNCTION FormatString$ (s#)
DECLARE SUB Dot.Display (VarA#, VarB#, VarC!)
DECLARE SUB Back.Space ()
Rem $Dynamic
DefDbl A-Z
On Error GoTo Error.Routine
On Timer(1) GoSub StatusLine
Timer On
Rem _Title "Prime Generstor"
Rem _ScreenMove _Middle
GoSub StatusLine
StartLoop:
Width 80, 25
Cls
Color 14
Print "Prime number generator v2.0a."
Color 15
Do
Print "Enter (T)est/(P)rint/(C)ount?";
Do
A$ = InKey$
If Len(A$) Then Exit Do
Loop
A$ = UCase$(A$)
If A$ = "T" Then
Print: PrintPrimes = -2
Do
Print "Enter test prime?";
T$ = Keyboard$
If CDbl(Val(T$)) < 32768 Then
T = CInt(Val(T$))
Else
T = CDbl(Val(T$))
End If
Select Case T
Case Is < 0, 0, 1 ' anything less than 2 is not a prime.
Print T; "is not prime."
Case 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37 ' short list of first 12 primes.
Print T; "is prime."
Case Else
S = 1024
Exit Do
End Select
Loop
Exit Do
End If
If A$ = "P" Then Print: PrintPrimes = -1: Exit Do
If A$ = "C" Then Print: PrintPrimes = 0: Exit Do
Print
Loop
Do
Print "Enter fast display(Y/N)?";
Do
A$ = InKey$
If Len(A$) Then Exit Do
Loop
A$ = UCase$(A$)
If A$ = "Y" Then Print: FastDisplay = -1: Exit Do
If A$ = "N" Then Print: FastDisplay = 0: Exit Do
Print
Loop
If PrintPrimes = -2 Then GoTo ContinueLoop
Do
Print "Upper prime limit(10-1000000)?";
U$ = Keyboard$
If CDbl(Val(U$)) < 32768 Then
U = CInt(Val(U$))
Else
U = CDbl(Val(U$))
End If
If U = 0 Then U = 1000000: Exit Do
If U >= 10 Then Exit Do
Loop
ContinueLoop:
Do
Print "Upper sieve limit(1024-32767)?";
S$ = Keyboard$
If CDbl(Val(S$)) < 32768 Then
S = CInt(Val(S$))
Else
S = CDbl(Val(S$))
End If
If S = 0 Then S = 1024: Exit Do
If S >= 1024 Then Exit Do
Loop
ReDim p(S) As Double
T! = Timer
Color 14
Print "Storing sieve array of "; FormatString$(S); " elements."
VarD = 0
VarE = 0
VarF! = Timer
StartTimer! = Timer
q = 0
Z = 1
Do
If FastDisplay = 0 Then
Elapsed! = Timer - StartTimer!
If Elapsed! < 0! Then Elapsed! = Elapsed! + 86400!
If Elapsed! >= 1! Then
Call Dot.Display(VarD, VarE, VarF!)
StartTimer! = Timer
End If
End If
Z = Z + 1
F = 0
For l = 2 To Int(Sqr(Z))
If Z / l = Int(Z / l) Then
F = -1
Exit For
End If
Next
If F = 0 Then
q = q + 1
p(q) = Z
End If
If q = S Then
Exit Do
End If
Loop
Do
If Pos(0) > 1 Then
Locate CsrLin, Pos(0) - 1, 0
Print " ";
Locate CsrLin, Pos(0) - 1, 1
Else
Exit Do
End If
Loop
' display calculated runtime.
Z! = Timer - T!
If Z! < 0! Then Z! = Z! + 86400!
If Z! > 0! Then
Z$ = Str$(Z!)
If InStr(Z$, ".") Then Z$ = Left$(Z$, InStr(Z$, ".") + 1)
Print " Runtime:"; Z$; " seconds."
End If
Print "Calculating primes.."
Print "Maximum prime: ";
x# = (p(S) * p(S))
Print FormatString$(x#)
Color 15
Print "Press <escape> to quit:"
If PrintPrimes = -2 Then
' check sieve arrays.
Z = T
GoSub IsPrime
Select Case F
Case 0
Print "Value "; FormatString$(T); " is prime."
Case -1
Print "Value "; FormatString$(T); " is not prime."
Case -2
Print "Array limit exceeded."
End Select
GoTo EndLoop
End If
If PrintPrimes Then
Print 2 ' first prime is always 2.
End If
VarD = 0
VarE = 0
VarF! = Timer
StartTimer! = Timer
c = 0
Z = 1
x = 0
Do
Z = Z + 2
q = 0
F = 0
Do
If FastDisplay = 0 Then
Elapsed! = Timer - StartTimer!
If Elapsed! < 0! Then Elapsed! = Elapsed! + 86400!
If Elapsed! >= 1! Then
Call Dot.Display(VarD, VarE, VarF!)
StartTimer! = Timer
End If
End If
q = q + 1
If q > S Then
Exit Do
End If
If p(q) > Int(Sqr(Z)) Then
Exit Do
End If
If Z / p(q) = Int(Z / p(q)) Then
F = -1
Exit Do
End If
Loop
If q > S Then
Exit Do
End If
If F = 0 Then
c = c + 1
If PrintPrimes Then
Print Z
End If
If InKey$ = Chr$(27) Then
Exit Do
End If
If Z > U Then
Exit Do
End If
If Z > (p(S) * p(S)) Then
Exit Do
End If
End If
Loop
' clear dots.
Do
If Pos(0) > 1 Then
Locate CsrLin, Pos(0) - 1, 0
Print " ";
Locate CsrLin, Pos(0) - 1, 1
Else
Exit Do
End If
Loop
' display totals.
Print "Last prime: ";
Print FormatString$(Z)
Print "Primes: ";
Print FormatString$(c + 1)
' display calculated runtime.
Z! = Timer - T!
If Z! < 0! Then Z! = Z! + 86400!
Z$ = Str$(Z!)
If InStr(Z$, ".") Then Z$ = Left$(Z$, InStr(Z$, ".") + 1)
Print " Runtime:"; Z$; " seconds."
' prompt to run again.
EndLoop:
Do
Color 15
Print "Run again(Y/N)";
Do
A$ = InKey$
If Len(A$) Then Exit Do
Loop
A$ = UCase$(A$)
If A$ = "Y" Then GoTo StartLoop
If A$ = "N" Then Exit Do
Print
Loop
GoSub ClearLine
Color 7
End
' standard error trap
Error.Routine:
Color 12
Print "Error"; Err;
If Err = 6 Then Print " Overflow";
Print
Color 7
Resume EndLoop
End
' display statusline in timer loop.
StatusLine:
X1 = CsrLin
Y1 = Pos(0)
Locate 25, 1
Print "Prime generator " + Date$ + " " + Time$;
If q > 0 Then
Print " Test:"; q; " ";
Else
Print Space$(15);
End If
Locate X1, Y1
Return
' clear statusline in timer loop.
ClearLine:
X1 = CsrLin
Y1 = Pos(0)
Locate 25, 1
Print Space$(79);
Locate X1, Y1
Return
' see if Z is prime. returns F as false if prime.
IsPrime:
q = 0
F = 0
' check in sieve array first.
For x = 1 To S
If Z = p(x) Then Return
Next
' calculate prime next.
Do
If FastDisplay = 0 Then
elapsed = Timer - starttimer
If elapsed < 0 Then elapsed = elapsed + 86400
If elapsed >= 1 Then
Call Dot.Display(VarD, VarE, VarF!)
starttimer = Timer
End If
End If
q = q + 1
If q > S Then
F = -2
Exit Do
End If
If p(q) > Int(Sqr(Z)) Then
Exit Do
End If
If Z / p(q) = Int(Z / p(q)) Then
F = -1
Exit Do
End If
Loop
' clear dots.
Do
If Pos(0) > 1 Then
Locate CsrLin, Pos(0) - 1, 0
Print " ";
Locate CsrLin, Pos(0) - 1, 1
Else
Exit Do
End If
Loop
Return
Sub Back.Space
If Pos(0) > 1 Then
Locate CsrLin, Pos(0) - 1, 0
Print " ";
Locate CsrLin, Pos(0) - 1, 1
End If
End Sub
Sub Dot.Display (VarA, VarB, VarC!)
VarG! = Timer - VarC!
If VarG! < 0! Then VarG! = VarG! + 86400!
If VarG! >= 1! Then
VarC! = Timer
If VarA = 0 Then
VarB = VarB + 1
Print ".";
If VarB = 5 Then
VarA = -1
VarB = 0
End If
Else
VarB = VarB + 1
Call Back.Space
Print " ";
Call Back.Space
If VarB = 5 Then
VarA = 0
VarB = 0
End If
End If
End If
End Sub
' formats a numeric string.
Function FormatString$ (s)
x$ = ""
s$ = Str$(s)
s$ = LTrim$(s$)
If InStr(s$, ".") Then s$ = Left$(s$, InStr(s$, ".") - 1)
For l = Len(s$) To 3 Step -3
x$ = Mid$(s$, l - 2, 3) + "," + x$
Next
If l > 0 Then
x$ = Mid$(s$, 1, l) + "," + x$
End If
If Len(s$) < 3 Then
x$ = s$
End If
If Right$(x$, 1) = "," Then
x$ = Left$(x$, Len(x$) - 1)
End If
FormatString$ = x$
End Function
' get inkey during timer loop.
Function Keyboard$
V$ = ""
Do
A$ = ""
Do
A$ = InKey$
If Len(A$) Then Exit Do
Loop
If A$ >= "0" And A$ <= "9" Then
V$ = V$ + A$
Print A$;
End If
If A$ = Chr$(8) Then ' backspace
If Len(V$) Then
V$ = Left$(V$, Len(V$) - 1)
X1 = CsrLin
Y1 = Pos(0)
Locate X1, Y1 - 1
Print " ";
Locate X1, Y1 - 1
End If
End If
If A$ = Chr$(27) Then
For V = 1 To Len(V$)
X1 = CsrLin
Y1 = Pos(0)
Locate X1, Y1 - 1
Print " ";
Locate X1, Y1 - 1
Next
V$ = ""
End If
If A$ = Chr$(13) Then Exit Do
Loop
Keyboard$ = V$
Print
End FunctionAn example of a small prime generator:
Code: (Select All)
Rem small prime number sieve.
DefLng A-Z
Rem $Dynamic
Dim p(1024) As Integer
For x = 2 To 1024
For l = x + x To 1024 Step x
If l <= 1024 Then
p(l) = -1
End If
Next
Next
For l = 2 To 1024
If p(l) = 0 Then Print l;
Next
End