how i can convert binary 128 bit to decimal??

i work in data encryption, but i don't know how to convert a 128 binary to decimal. i try bin2dec and its not work and the error massage tell me : "Binary string must be 52 bits or less". please help

 a=dec2bin(7,128)
 b=bin2dec(a) 

 Error using bin2dec (line 36)
 Binary string must be 52 bits or less.

[nail]

Thank you all

nothing works

but i change my code variables to make the output range (8-52) if i know how to make it bigger (64,128,.....) i will change just the conditions :)

you are help me so much

but i want to get 128 bits of it as binary of string data example

1= 00110001

2= 00110010

a= 01100001

b= 01100010

A= 01000001

Answer 1

[James Tursa]

Double precision numbers only have a 52-bit mantissa (+1 hidden leading bit), hence the error. A uint64 has 64 bits, and that is the max you can have for numeric types. To deal with this many bits in a number you will need to use something else. E.g either the Symbolic Toolbox, or use the Variable Precision Integer FEX submission by John D'Errico:

http://www.mathworks.com/matlabcentral/fileexchange/22725-variable-precision-integer-arithmetic

[nail]

Thank you James Tursa but i want to get something help me in my code. are you want to say its impossible ?? thank you again

[James Tursa]

I don't understand your comment. If you want a single variable to hold the decimal value of a 128-bit binary string, you can't do it with numeric types in MATLAB because there aren't enough bits available. You could use one of the methods I proposed, or perhaps break up your problem into 64-bit chunks and use uint64 types.

Answer 2

[Hind Thanoon]

Hello nail.. try the following code:

a=dec2bin(7,128); b=bin2dec(a(1:24))*2^104+bin2dec(a(25:76))*2^52+bin2dec(a(77:128))*2^0;

this will help you to solve your problem you will convert each 52 bit separately and then accumulate the result like the following example: a=1001=9, if I need to convert each 2bit then I will say bin2dec(10)*2^2+bin2dec(01)*2^0 {bin2dec(a(1:2))*2^2+bin2dec(a(3:4))*2^0} the result will be: 2*2^2+1*2^0=9

[James Tursa]

There are not enough bits in a double variable to hold the exact value of a 128-bit binary string, so your method of breaking things up and accumulating the result will not work in general.

[Radwa]

I work in encryption also, how u solve ur problem?