BIN2DEC conversion for large binary numbers

A

ahmedmidany

Hello All,

I need your help, i want to convert large binary numbers using excel
but whenever i use the BIN2DEC function the result is negative which
is not correct.

Ex. BIN2DEC(1100110110) the result is -202 but if i use the calculator
the result is 822 which is the correct value

Any ideas? what shall i do to have the correct value?

Thanks in advance
A.M.
 
M

Mike H

Hi,

Well I think it's 822 and my calculator confirms that and like you I get
-202. Someone will no doubt explain why but in the meantime use this

=SUMPRODUCT(MID("0"&A1,ROW(INDIRECT("1:"&LEN("0"&A1))),1)*2^(LEN("0"&A1)-ROW(INDIRECT("1:"&LEN("0"&A1)))))

Where your binary number is in A1

Mike
 
R

Ron Rosenfeld

Hello All,

I need your help, i want to convert large binary numbers using excel
but whenever i use the BIN2DEC function the result is negative which
is not correct.

Ex. BIN2DEC(1100110110) the result is -202 but if i use the calculator
the result is 822 which is the correct value

Any ideas? what shall i do to have the correct value?

Thanks in advance
A.M.
Click to expand...

There is a way to use BIN2DEC with large numbers, but I can't recall it.

You could use:

=SUMPRODUCT(--MID(A1,LEN(A1)+1-ROW(INDIRECT("1:"&LEN(A1))),1),(2^(ROW(INDIRECT("1:"&LEN(A1)))-1)))

Just be aware that if your value is more than 15 digits, you must enter it as
text.
--ron
 
P

Pete_UK

XL Help tells you why the answer is wrong - you are limited to 10 bits
and the msb is the sign bit. Chop the number up into bytes (8 bits)
and treat each part separately, remembering to multiply by 256 for the
upper byte.

Hope this helps.

Pete
 
D

David Biddulph

I guess that you haven't looked at help for the BIN2DEC function?

"Number is the binary number you want to convert. Number cannot contain
more than 10 characters (10 bits). The most significant bit of number is the
sign bit. The remaining 9 bits are magnitude bits. Negative numbers are
represented using two's-complement notation."

Perhaps you might want to split your 10 digit string in half and use
=BIN2DEC(LEFT(A2,LEN(A2)-5))*2^5+BIN2DEC(RIGHT(A2,5))
 
M

Mike H

Pete,

I just checked E2003 and you are correct but there is no such explanation of
this limitation in E2007 help reproduced below

A number system is a systematic way to represent numbers with symbolic
characters and uses a base value to conveniently group numbers in compact
form. The most common number system is decimal, which has a base value of 10,
and a symbolic character set of 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. However,
there are other number systems, and they can be more efficient to use for a
specific purpose. For example, because computers use Boolean logic to perform
calculations and operations, they use the binary number system, which has a
base value of 2.

Microsoft Office Excel has several functions that you can use to convert
numbers to and from the following number systems:

Mike
 
M

Mike H

I guess that you haven't looked at help for the BIN2DEC function?

I did and while it is mentioned in e2003 there is no equivalent comment in
e2007 help.

Mike
 
R

Ron Rosenfeld

I just checked E2003 and you are correct but there is no such explanation of
this limitation in E2007 help reproduced below
Click to expand...

That's funny. With Excel 2007, when I look at HELP for BIN2DEC, I see:

Number is the binary number you want to convert. Number cannot contain more
than 10 characters (10 bits). The most significant bit of number is the sign
bit. The remaining 9 bits are magnitude bits. Negative numbers are represented
using two's-complement notation.

Seems pretty clear to me.
--ron
 
M

Mike H

Ron,

100% definitely not in my E2007 just the intro header I posted in my other
post then a description of the syntax for each of the formulae.

Excel 2007 (12.0.6514.5000) SP2 MSO (12.0.6425.1000)

Mike
 
M

Mike H

Ron,

It now becomes almost surreal the way Excel help works. Convinced that
certainly you and probably not myself are mad I checked again.

I enter BIN2DEC in excel help and I get a help category

Convert numbers to different number systems

Not unreasonably (I think) I click this and there is a list of all the
conversion formula with the header I posted in my other post i.e. NO mention
of the limitation 'feature' of this formula.

Also when I enter BIN2DEC I see an option

List of worksheet functions (by category)

When I click this and then click 'Engineering functions' and navigate to
BIN2DEC the formula is described with the limitation.

So it seems that in E2007 it depends on where you look for help is a
critical factor in getting a precise answer. Well done Microsoft.

Mike
 
P

Pete_UK

Ah, so it IS better then, Mike !!! <ebg>

Pete

Ron,

It now becomes almost surreal the way Excel help works. Convinced that
certainly you and probably not myself are mad I checked again.

I enter BIN2DEC in excel help and I get a help category

Convert numbers to different number systems

Not unreasonably (I think) I click this and there is a list of all the
conversion formula with the header I posted in my other post i.e. NO mention
of the limitation 'feature' of this formula.

Also when I enter BIN2DEC I see an option

List of worksheet functions (by category)

When I click this and then click 'Engineering functions' and navigate to
BIN2DEC the formula is described with the limitation.

So it seems that in E2007 it depends on where you look for help is a
critical factor in getting a precise answer. Well done Microsoft.

Mike







- Show quoted text -
Click to expand...
 
R

Ron Rosenfeld

Ron,

It now becomes almost surreal the way Excel help works. Convinced that
certainly you and probably not myself are mad I checked again.

I enter BIN2DEC in excel help and I get a help category

Convert numbers to different number systems

Not unreasonably (I think) I click this and there is a list of all the
conversion formula with the header I posted in my other post i.e. NO mention
of the limitation 'feature' of this formula.

Also when I enter BIN2DEC I see an option

List of worksheet functions (by category)

When I click this and then click 'Engineering functions' and navigate to
BIN2DEC the formula is described with the limitation.

So it seems that in E2007 it depends on where you look for help is a
critical factor in getting a precise answer. Well done Microsoft.

Mike
Click to expand...

Mike,

The first sequence I went through was to access help for BIN2DEC using the
function wizard. ie. Type =bin2dec in the function bar; select the Fx; select
HELP on the dialog box. This brings up help for that particular function.

So then I typed bin2dec in Excel help -->

==========================================
Engineering functions (reference)
Help > Function reference > Engineering

Convert numbers to different number systems
Help > Formula and name basics > Examples of formulas > Conversion

List of worksheet functions (alphabetical)
Help > Function reference

List of worksheet functions (by category)
Help > Function reference
=====================================

Selection #2 was the obvious and, in addition to the information you posted
earlier, also had a "What do you want to do?" line.

I select "Convert a binary number to decimal" which takes me down to an area
which gives both an example, and an option to select the details of the BIN2DEC
function. When I select that hyperlink, it takes me to the info on the BIN2DEC
function including its limitations.

To me, it seems like a logical progression.

If you're not seeing that, I would suspect a problem with Internet Explorer. I
have had a problem with display of HELP files; the usual solution has to do
with clearing temporary Internet files, etc. However, I progressed through a
variety of solutions until the next step was to reinstall Windows XP. (I
didn't do that since I was planning to upgrade to Windows 7 anyway, and that
solved the problem).


--ron
 
R

Rick Rothstein

Below is a UDF that will handle up to a 96-bit binary number (decimal value
79228162514264337593543950335) which I'm guessing is way more than you will
ever need.<g> The code is efficient (looping only as many times as necessary
to process the passed in binary value), so don't worry about it being able
to handle such a large binary value. The function returns a real numeric
value up to 9999999999 after which it returns text representations of the
calculated number.

Function BinToDec(BinaryString As String) As Variant
Dim X As Integer
Const TwoToThe48 As Variant = 281474976710656#
For X = 0 To Len(BinaryString) - 1
If X > 48 Then
BinToDec = CDec(BinToDec) + Val(Mid(BinaryString, _
Len(BinaryString) - X, 1)) * _
TwoToThe48 * CDec(2 ^ (X - 48))
Else
BinToDec = CDec(BinToDec) + Val(Mid(BinaryString, _
Len(BinaryString) - X, 1)) * CDec(2 ^ X)
End If
Next
If Len(BinToDec) > 10 Then BinToDec = CStr(BinToDec)
End Function
 
D

Dana DeLouis

Below is a UDF that will handle up to a 96-bit binary number (decimal
value 79228162514264337593543950335) which I'm guessing is way more than
you will ever need.<g> The code is efficient (looping only as many times
as necessary to process the passed in binary value), so don't worry
about it being able to handle such a large binary value. The function
returns a real numeric value up to 9999999999 after which it returns
text representations of the calculated number.

Function BinToDec(BinaryString As String) As Variant
Dim X As Integer
Const TwoToThe48 As Variant = 281474976710656#
For X = 0 To Len(BinaryString) - 1
If X > 48 Then
BinToDec = CDec(BinToDec) + Val(Mid(BinaryString, _
Len(BinaryString) - X, 1)) * _
TwoToThe48 * CDec(2 ^ (X - 48))
Else
BinToDec = CDec(BinToDec) + Val(Mid(BinaryString, _
Len(BinaryString) - X, 1)) * CDec(2 ^ X)
End If
Next
If Len(BinToDec) > 10 Then BinToDec = CStr(BinToDec)
End Function
Click to expand...


Hi. Just throwing out another idea. Len(BinaryString) is more of a
constant (calculated each loop), and power (ie 2^x) is sometimes
considered "slower."
This has no error checking.

Function Bin2Dec(str As String)
Dim S As String
Dim P As Long
Dim K As Variant
Dim Ans As Variant

S = StrReverse(str)
K = CDec(1)

For P = 1 To Len(S) - 1
Ans = Ans + Val(Mid$(S, P, 1)) * K
K = K * 2
Next P
Bin2Dec = Ans + Val(Mid$(S, P, 1)) * K
End Function



Sub TestIt()
Dim S As String
S = WorksheetFunction.Rept("1", 96)
Debug.Print Bin2Dec(S)

Mid(S, 3, 1) = 0
Debug.Print Bin2Dec(S)

Mid(S, 96, 1) = 0
Debug.Print Bin2Dec(S)

Mid(S, 95, 1) = 0
Debug.Print Bin2Dec(S)
Debug.Print "= = = = = = = ="
End Sub


Returns:

79228162514264337593543950335
69324642199981295394350956543
69324642199981295394350956542
69324642199981295394350956540
= = = = = = = =

Again, just an idea.
Dana DeLouis
 

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