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FloSG

maximal number range

5 posts in this topic

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

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#2 ·  Posted (edited)

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 by water

My UDFs and Tutorials:

Spoiler

UDFs:
Active Directory (NEW 2017-04-18 - Version 1.4.8.0) - Download - General Help & Support - Example Scripts - Wiki
OutlookEX (NEW 2017-02-27 - Version 1.3.1.0) - Download - General Help & Support - Example Scripts - Wiki
ExcelChart (2015-04-01 - Version 0.4.0.0) - Download - General Help & Support - Example Scripts
Excel - Example Scripts - Wiki
Word - Wiki
PowerPoint (2015-06-06 - Version 0.0.5.0) - Download - General Help & Support

Tutorials:
ADO - Wiki

 

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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

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#4 ·  Posted (edited)

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 by jchd

This wonderful site allows debugging and testing regular expressions (many flavors available). An absolute must have in your bookmarks.
Another excellent RegExp tutorial. Don't forget downloading your copy of up-to-date pcretest.exe and pcregrep.exe here
RegExp tutorial: enough to get started
PCRE v8.33 regexp documentation latest available release and currently implemented in AutoIt beta.

SQLitespeed is another feature-rich premier SQLite manager (includes import/export). Well worth a try.
SQLite Expert (freeware Personal Edition or payware Pro version) is a very useful SQLite database manager.
An excellent eBook covering almost every aspect of SQLite3: a must-read for anyone doing serious work.
SQL tutorial (covers "generic" SQL, but most of it applies to SQLite as well)
A work-in-progress SQLite3 tutorial. Don't miss other LxyzTHW pages!
SQLite official website with full documentation (may be newer than the SQLite library that comes standard with AutoIt)

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