maximal number range

[FloSG]

Hi,

I'm a newcomer in AutoIt. I tried to make a programme that recognizes prime numbers.

The program works great, except of large numbers. What is wrong in the programme? Are there restrictions with large numbers, these I don't know?

Here is my code:

$number = InputBox("Prime number", "Please enter a number: ")
for $i = 2 to $number-1
    if Mod($number, $i) = 0 then
        MsgBox(0, "Prime", "The number " & $number & " isn't a prime number, because it's divisible  by " & $i)
        Exit
    EndIf
next
MsgBox(0, "Prime number", "The number " & $number & " is a prime number!")

Thanks

rgds FloSG

[water]

The program works great, except of large numbers.

I suspect it's because of the way AutoIt handles large numbers. These are the current limitations:

Number range (floating point): 1.7E–308 to 1.7E+308 with 15-digit precision

Number range (integers): 64-bit signed integer

BTW: There is a Prime UDF (User Defined Functions) here.

Edited May 31, 2010 by water

[FloSG]

I suspect it's because of the way AutoIt handles large numbers. These are the current limitations:

Number range (floating point): 1.7E–308 to 1.7E+308 with 15-digit precision

Number range (integers): 64-bit signed integer

BTW: There is a Prime UDF (User Defined Functions) here.

Thanks

[jchd]

Also, you really should make your trial division loop a little more clever.

But even then, your algorithm is a bit naive (even for numbers that number theorists would call small). If you run it on, for instance, the smallest prime larger than 2^53, you set yourself up for a 9007199254740997 loop. Don't hold your breath!

Have a look a the prime UDF.

Edit: I've no idea what that junk was... O yes I now see: it was a mistake trying to copy/paste the result from a Mathematica notebook, where I selected "copy" instead of "copy as text". It silently pasted garbage here. Sorry for pooping here!

Edited May 31, 2010 by jchd

[AdmiralAlkex]

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