VB/WinAPI, Factorial of 10000

Mark Keog
#1 / 16

Factorial of 10000

Ok,

I've been issued the challenge to get the above. THe problemis what should I
store the result as? The returned number, verified in Smalltalk, is a 36000
and something digit int!

Any ideas?

Tue, 04 Feb 2003 08:59:52 GMT

Drac
#2 / 16

Factorial of 10000

released on Fri, 18 Aug 2000 10:59:52 +1000 bearing the
following fruit:

Quote:

>Ok,

>I've been issued the challenge to get the above. THe problemis what should I
>store the result as? The returned number, verified in SmallTalk, is a 36000
>and something digit int!

>Any ideas?

Isn't the factorial of 3 = 3 * 2 * 1 = 6 ?

Because if it is then 36,000 certainly isn't
the factorial of 10,000

The windows calculator has a factorial function,
take a look for a more realistic value.

D

Tue, 04 Feb 2003 03:00:00 GMT

rumpol
#3 / 16

Factorial of 10000

Quote:

>>The returned number, verified in SmallTalk, is a 36000
>>and something digit int!
>Isn't the factorial of 3 = 3 * 2 * 1 = 6 ?

>Because if it is then 36,000 certainly isn't
>the factorial of 10,000

>The windows calculator has a factorial function,
>take a look for a more realistic value.

maybe if he'd said "an integer with 36000+ digits" you wouldn't have
misread it?

Tue, 04 Feb 2003 03:00:00 GMT

Ron Lessnic
#4 / 16

Factorial of 10000

Do a search on the binary coded decimal system (BCD). Each decimal digit
position is stored as 4 bits. Thus a byte will hold two digits. So an
integer of length 36000 decimal digits long can be stored in a 18K byte
array. So to display the BIG answer you loop thru the array decoding each
byte into its two equivalent decimals and build up a string of VERY LONG
length shove it in multiline enabled scrollable text box and you are home
free.

Real challenge will be the coding to do the multiplication of BCD numbers,
but maybe there is some math library (dll) you can find.

HTH

Ron

Quote:

> Ok,

> I've been issued the challenge to get the above. THe problemis what should
I
> store the result as? The returned number, verified in SmallTalk, is a
36000
> and something digit int!

> Any ideas?

Tue, 04 Feb 2003 03:00:00 GMT

Gale Gree
#5 / 16

Factorial of 10000

Hi.

Quote:

>Isn't the factorial of 3 = 3 * 2 * 1 = 6 ?

>Because if it is then 36,000 certainly isn't
>the factorial of 10,000

I think you missed a vital word in Mark's post - it isn't a 36,000-odd
number, it's a 36,000-odd *digit* number!

I'm sure I could devise an algorithm but I'm afraid life's too short
and clients are too demanding. <g>

Gale.

Tue, 04 Feb 2003 03:00:00 GMT

Drac
#6 / 16

Factorial of 10000

released on Fri, 18 Aug 2000 13:45:06 +0100 bearing the
following fruit:

Quote:

>Hi.

>>Isn't the factorial of 3 = 3 * 2 * 1 = 6 ?

>>Because if it is then 36,000 certainly isn't
>>the factorial of 10,000

>I think you missed a vital word in Mark's post - it isn't a 36,000-odd
>number, it's a 36,000-odd *digit* number!

>I'm sure I could devise an algorithm but I'm afraid life's too short
>and clients are too demanding. <g>

>Gale.

Yep, as rumpole suggests, I did misunderstand
what was written. <bows head in shame>

D

Tue, 04 Feb 2003 03:00:00 GMT

Brent W.J. Macki
#7 / 16

Factorial of 10000

10000! = 2.8462596809170545189064132121 x 10^35659
As verified using Calc.exe on Win98SE

Brent

Quote:

> released on Fri, 18 Aug 2000 10:59:52 +1000 bearing the
> following fruit:

> >Ok,

> >I've been issued the challenge to get the above. THe problemis what
should I
> >store the result as? The returned number, verified in SmallTalk, is a
36000
> >and something digit int!

> >Any ideas?

> Isn't the factorial of 3 = 3 * 2 * 1 = 6 ?

> Because if it is then 36,000 certainly isn't
> the factorial of 10,000

> The windows calculator has a factorial function,
> take a look for a more realistic value.

> D

Tue, 04 Feb 2003 03:00:00 GMT

Mark Heat
#8 / 16

Factorial of 10000

A simple way is to use strings to store your numbers and multiply as though
you were doing it by hand.
There are, of course, much more efficient ways than this but this should
point you in the right sort of direction.
Mark

Public Function Multiply(arg1 As String, arg2 As String) As String
Dim i As Integer
Dim j As Integer
Dim str1 As String
Dim str2 As String
Dim strTotal As String
Dim strTemp As String
Dim iCarry As Integer
Dim iTemp As Integer

str1 = StrReverse(arg1)
str2 = StrReverse(arg2)
For i = 1 To Len(str1)
iCarry = 0
strTemp = String(i - 1, "0")
For j = 1 To Len(str2)
iTemp = CInt(Mid$(str2, j, 1)) * CInt(Mid$(str1, i, 1)) + iCarry
strTemp = strTemp & (iTemp Mod 10)
iCarry = iTemp \ 10
Next j
If iCarry > 0 Then
strTemp = strTemp & iCarry
End If
strTotal = AddRevString(strTotal, strTemp)
Next i

Multiply = StrReverse(strTotal)
End Function

Public Function AddRevString(arg1 As String, arg2 As String) As String
Dim i As Integer
Dim strTotal As String
Dim iCarry As Integer
Dim iMax As Integer
Dim iTemp As Integer

iMax = Len(arg1)
If Len(arg2) > iMax Then
iMax = Len(arg2)
End If

iCarry = 0

For i = 1 To iMax
iTemp = Val(Mid$(arg2, i, 1)) + Val(Mid$(arg1, i, 1)) + iCarry
strTotal = strTotal & (iTemp Mod 10)
iCarry = iTemp \ 10
Next i
If iCarry > 0 Then
strTotal = strTotal & iCarry
End If
AddRevString = strTotal
End Function

Quote:

> Ok,

> I've been issued the challenge to get the above. THe problemis what should
I
> store the result as? The returned number, verified in SmallTalk, is a
36000
> and something digit int!

> Any ideas?

Tue, 04 Feb 2003 03:00:00 GMT

Mark Heat
#9 / 16

Factorial of 10000

I ought to point out that this will take ages to calculate factorial 10000
(quite possibly a couple of days - depending on your computer speed)
If you can program in C you will be able to speed this up considerably.

Mark

Quote:

> A simple way is to use strings to store your numbers and multiply as
though
> you were doing it by hand.
> There are, of course, much more efficient ways than this but this should
> point you in the right sort of direction.
> Mark

> Public Function Multiply(arg1 As String, arg2 As String) As String
> Dim i As Integer
> Dim j As Integer
> Dim str1 As String
> Dim str2 As String
> Dim strTotal As String
> Dim strTemp As String
> Dim iCarry As Integer
> Dim iTemp As Integer

> str1 = StrReverse(arg1)
> str2 = StrReverse(arg2)
> For i = 1 To Len(str1)
> iCarry = 0
> strTemp = String(i - 1, "0")
> For j = 1 To Len(str2)
> iTemp = CInt(Mid$(str2, j, 1)) * CInt(Mid$(str1, i, 1)) + iCarry
> strTemp = strTemp & (iTemp Mod 10)
> iCarry = iTemp \ 10
> Next j
> If iCarry > 0 Then
> strTemp = strTemp & iCarry
> End If
> strTotal = AddRevString(strTotal, strTemp)
> Next i

> Multiply = StrReverse(strTotal)
> End Function

> Public Function AddRevString(arg1 As String, arg2 As String) As String
> Dim i As Integer
> Dim strTotal As String
> Dim iCarry As Integer
> Dim iMax As Integer
> Dim iTemp As Integer

> iMax = Len(arg1)
> If Len(arg2) > iMax Then
> iMax = Len(arg2)
> End If

> iCarry = 0

> For i = 1 To iMax
> iTemp = Val(Mid$(arg2, i, 1)) + Val(Mid$(arg1, i, 1)) + iCarry
> strTotal = strTotal & (iTemp Mod 10)
> iCarry = iTemp \ 10
> Next i
> If iCarry > 0 Then
> strTotal = strTotal & iCarry
> End If
> AddRevString = strTotal
> End Function

> > Ok,

> > I've been issued the challenge to get the above. THe problemis what
should
> I
> > store the result as? The returned number, verified in SmallTalk, is a
> 36000
> > and something digit int!

> > Any ideas?

Tue, 04 Feb 2003 03:00:00 GMT

Ron
#10 / 16

Factorial of 10000

Since it takes about 5 seconds for Calc.exe to come up with that number one
has to assume the result is from Stirlings formula which is only an
"approximation" for large numbers. To do this calculation for real would
take ALOT longer. Also I assume the original poster wanted to do it in VB

Ron

Quote:

> 10000! = 2.8462596809170545189064132121 x 10^35659
> As verified using Calc.exe on Win98SE

> Brent

> > released on Fri, 18 Aug 2000 10:59:52 +1000 bearing the
> > following fruit:

> > >Ok,

> > >I've been issued the challenge to get the above. THe problemis what
> should I
> > >store the result as? The returned number, verified in SmallTalk, is a
> 36000
> > >and something digit int!

> > >Any ideas?

> > Isn't the factorial of 3 = 3 * 2 * 1 = 6 ?

> > Because if it is then 36,000 certainly isn't
> > the factorial of 10,000

> > The windows calculator has a factorial function,
> > take a look for a more realistic value.

> > D

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Wed, 05 Feb 2003 03:00:00 GMT

Scott Seligma
#11 / 16

Factorial of 10000

Quote:

> I've been issued the challenge to get the above. THe problemis what should
I
> store the result as? The returned number, verified in SmallTalk, is a
36000
> and something digit int!

Well, if the challenge doesn't specify a time limit, then the easist
solution is store the number as a string, and write a couple of functions
that can multiple and add strings (without converting the whole number to an
intrinsic type, but rather adding as a normal person would have to add or
multiply a big number).

I just wrote a little program that did this, and to find the factorial of
10,000 took a few hours, but it does work.

To speed things up, you generally take the same idea, but instead of
creating a long string like "123123", you create an array of numbers, say
using the byte type, and treat your big number as a base 255 number. This
way each entry in the array is one digit of the number

The trick becoms to convert a big number like this into a base 10 number.
There are books that describe this technique, and have some code showing how
it's done (mostly in C/C++ though).

Hope this helps.

--
Scott

Wed, 05 Feb 2003 03:00:00 GMT

Jeff Ashle
#12 / 16

Factorial of 10000

Quote:

> The trick becoms to convert a big number like this into a base 10 number.

No kidding! I've never used base 255 . . .

Wed, 05 Feb 2003 03:00:00 GMT

Arie Bakke
#13 / 16

Factorial of 10000

Is your problem solved? I've made some years ago a program to calculate
2^300 and that must be about the same problem. I can look for it, if
your problem isn't solved yet.

Please send a e-mail if you need it.

Arie Bakker

Quote:

> Ok,

> I've been issued the challenge to get the above. THe problemis what should I
> store the result as? The returned number, verified in SmallTalk, is a 36000
> and something digit int!

> Any ideas?

Fri, 07 Feb 2003 07:08:24 GMT

Rui Martins dos Santo
#14 / 16

Factorial of 10000

Windows 2000 Calc:
10000! = 2,8462596809170545189064132121199e+35659

Quote:

> 10000! = 2.8462596809170545189064132121 x 10^35659
> As verified using Calc.exe on Win98SE

> Brent

> > released on Fri, 18 Aug 2000 10:59:52 +1000 bearing the
> > following fruit:

> > >Ok,

> > >I've been issued the challenge to get the above. THe problemis what
> should I
> > >store the result as? The returned number, verified in SmallTalk, is a
> 36000
> > >and something digit int!

> > >Any ideas?

> > Isn't the factorial of 3 = 3 * 2 * 1 = 6 ?

> > Because if it is then 36,000 certainly isn't
> > the factorial of 10,000

> > The windows calculator has a factorial function,
> > take a look for a more realistic value.

> > D

Fri, 07 Feb 2003 03:00:00 GMT

Jeff Ashle
#15 / 16

Factorial of 10000

Well, that's a fair approximation . . .

Quote:

> Windows 2000 Calc:
> 10000! = 2,8462596809170545189064132121199e+35659

Fri, 07 Feb 2003 03:00:00 GMT