MATLAB: How to set individual bits in 64-bit double-precision floating number

MATLAB

Hi everyone,

I am wondering if it is possible to set individual bits in 64-bit double-precision floating number in MATLAB.

I know that I can use "format hex" to read the bits. But how can I set it?

Thanks Kevin

Best Answer

Example:

typecast(bitset(typecast(pi,'uint64'),53,1),'double')

Bit numbering is 64 for the most significant bit, down to 1 for the least significant bit.

As the IEEE 754 floating point representation is being altered, the change I made here of effectively adding 1 to the exponent resulting in doubling the result (because IEEE 754 has binary representation, not decimal representation.)

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It looks like your hexadecimal values are the representation of a single precision IEEE 754 number, in little endian format.

hexvalues = ['BF6E23F8';'3CCCE6BD';'BF6E158D';'C1C63C18']
hexbits = uint32(hex2dec(hexvalues));       %convert hexadecimal to 32-bit integer representation
[~, ~, endianness] = computer;
if endianness == 'B'
   hexbits = swapbytes(hexbits);            %on a big-endian computer, switch endianness
end
hexassingle = typecast(hexbits, 'single')   %cast from integer to single

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