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Converting "twos complement" - decimal to actual twos complement and back to decimal

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Vinci
Vinci 2014-8-29
评论： nima nabavi 2021-8-11
Hello there
I've been working on a god damn binary-decimal conversion for at least three hours now so please help me out.
I imported a very large .csv file where the columns represent 32bit twos complement but are actual decimal values. So the very first element for example is 4.294.721.774 instead of an awful lot of ones and zeros.
In order to convert this number to the actual real value I tried the following:
% q object for 32bit precision
q = quantizier([32 31]);
% test with first element
num = 4294721774;
bin = de2bi(num, 'left-msb');
% convert binary array to string
str_bin = mat2str(bin);
% cut lead, tail and spaces
str_bin = str_bin(2:end-1);
str_bin = strrep(str_bin, ' ', '');
% convert back
output = bin2num(q, str_bin);
But not only is this highly inefficient, it also doesn't work... Any suggestions?

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采纳的回答

Iain
Iain 2014-8-29
Ah. Try:
typecast(uint32(4294721774),'int32')
I'm sure someone mentioned a faster version was in file exchange somewhere.

更多回答（2 个）

Iain
Iain 2014-8-29
Sounds like you just want to read the value as a signed 32 bit integer....
integer_with_32_bits = int32(4294721774)
Vinci
Vinci 2014-8-29
Sadly no because int32 just gives me the saturated int32 value "2.147.483.647".
What I actually want is the answer -245.522 which (if I just calculated that correctly) is the answer of the conversion
4.294.721.774 -> as binary -> interpret as twos complement -> decimal

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