XProfan

WindowTitle "Primfaktorisierung und Primtest mit der Wheel-Methode"
'Q: https://en.wikipedia.org/wiki/Wheel_factorization
Cls:font 2:appendmenubar 100,"Zahl < 2147483647 , 0 = Test, -1 = Ende"
declare v&,factors&[],k&,i&,in$,n&,plus&[8],check!
'Init: Das immer gleiche Rad für ein 3er-Wheel:
plus&[1]=4:plus&[2]=2:plus&[3]=4:plus&[4]=2
plus&[5]=4:plus&[6]=6:plus&[7]=2:plus&[8]=6

Repeat

    Eingabe:
    print " Zahl = ";:input in$

    if val(in$)>2147483647:cls:goto "Eingabe":endif

        n&=val(in$):case n&=-1:End
        case n&=0:n&=223092870
        FactorWheel(abs(n&))
        ShowOutput

    until 0

    Proc FactorWheel :parameters n&

        clear factors&[]:case n&<1:return:declare k&,i&,v&
        ' Beispiel 3er-Wheel:
        :whilenot n& mod 2:inc v&:factors&[v&]=2:n&=n&\2:Endwhile
        :whilenot n& mod 3:inc v&:factors&[v&]=3:n&=n&\3:Endwhile
        :whilenot n& mod 5:inc v&:factors&[v&]=5:n&=n&\5:Endwhile
        k&=7:i&=1

        while sqr(k&)<=n&

            ifnot n& mod k&:inc v&:factors&[v&]=k&:n&=n&\k&

                else:k&=k&+plus&[i&]:if i&<8:inc i&:else:i&=1:endif

            endif

            Endwhile: inc v&:factors&[v&]=n&

        Endproc

        Proc ShowOutput :case n&<1:return:print " ";n&;" = ";

            var s&=sizeof(factors&[])-1:s&=s&-(factors&[s&]=1)

            Whileloop s&:print factors&[&Loop];

                case &Loop<s&:print " ";chr$(215);" ";
                case %pos>54:print "\n  ";
                endwhile : case factors&[s&]=n&:print " (prim!)";

                if %csrlin>20:waitinput:cls:endif:print

                Endproc