Hex to float like python struct.unpack()
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Sebastian Thuné
on 16 Sep 2020
Answered: James Tursa
on 16 Sep 2020
Hi
I'm trying to convert a hex string to a float in the same manner python function struct.unpack(), https://docs.python.org/3/library/struct.html , which is using the IEEE754 binary32 0r 64 depending on foat or double.
As an example I have
hex = 'C956F53D'
When i run it in a struct.unpack() i get the value:
data = 0.1198
And this is correct. However, when i try the following matlab function i get something totally different.
>> hex2dec(hex)
ans =
3.3779e+09
>> typecast(uint32(hex2dec(hex)),'single')
ans =
single
-8.8047e+05
Does anybody know the difference or what I'm doing wrong?
Thanks!
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Accepted Answer
Ameer Hamza
on 16 Sep 2020
This is the correct way
hex = 'C956F53D';
x = hex2dec(reshape(hex, 2, []).');
dec = typecast(uint8(x), 'single')
2 Comments
Ameer Hamza
on 16 Sep 2020
Edited: Ameer Hamza
on 16 Sep 2020
Yes, you need to convert it into an uint8 array. Then MATLAB reads the bytes from the input array and converts those bytes into 'single'. It is pretty similar to pointer typecasting in C.
I am glad to be of help!
More Answers (1)
James Tursa
on 16 Sep 2020
Could be a Big Endian vs Little Endian thing. E.g., inserting a swapbytes( ) step:
>> hex = 'C956F53D'
hex =
'C956F53D'
>> typecast(swapbytes(uint32(hex2dec(hex))),'single')
ans =
single
0.1198
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