Hi i have questions " i want function like unit 64 but generate 56 bit"

Hi i have questions " i want function like unit 64 but generate 56 bit"

[Rik]

You mean you want a 56 bit unsigned integer data type? Why exactly can't you use uint64 instead?

[ghibeche]

Yes I mean this , because i need 56 bit for an initial value for a program like DES. I don't know if i can convey my idea to you

[ghibeche]

function val=Tab2Val(TB)
n=uint64(length(TB));
val=[n-1:-1:0];
val=(2.^val).*uint64(TB);
val=sum(val,'native');
end
[Here i need the output to be 56 bits ]

[John D'Errico]

Sorry, but there is no uint56 data type in MATLAB. Could you create one? Well yes. But then you would also need to program ALL interactions with that datatype. How to add, subtract, multiply, divide, display the numbers, etc.

Far better to just use uint64.

What the code you wrote is suposed to do, I am not at all sure. Are you trying to extract the bits? For example...

N = uint64(17)^12

N = uint64 582622237229761

log2(double(N))

ans = 49.0496

This is an integer smaller than 2^56, since the log base 2 is approximately 49.

And dec2bin can extract the desired 56 bits. There are leading zero bits, but that is what you want.

dec2bin(N,56)

ans = '00000010000100011110010001001111011111010000001011000001'

[ghibeche]

Thank you for this information