help with single precision floating point arithmetic

Hello Can you help me with the single precision floating point arithmetic in matlab I need to generate twiddle factors and obtain the output in the binary format( which is the standard IEEE 754 single precision 32-bit floating point format).Is there any function in MATLAB that will directly convert any value such as sine(pi/4)into the single precision format?
Thanks!

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Titus Edelhofer
Titus Edelhofer le 9 Nov 2011

0 votes

Hi,
guess what: the function is called 'single' ;-).
Titus
You do need to be careful with MATLAB and converting to single. Potentially not obvious is that
isequal(single(pi*pi), single(pi)*single(pi))
Also, I believe that in some cases single precision numbers are converted to double precision during calcualtions
Aparna
Aparna le 9 Nov 2011

0 votes

@titus , i tried using the function but it doesn't produce the output in the 32 bit precision floating point format.
p.s. i need the output in binary
thanks for helping me with this.
Hi Aparna,
I understand:
num2hex(single(pi))
Is that what you are looking for?
Titus
Aparna
Aparna le 9 Nov 2011

0 votes

hey! no i do not want the answer in Hexadecimal format i need it in binary 32 bit format. Could you help me with that?

4 commentaires

binary 32 bit format? So 32 zeros and ones?
dec2bin(hex2dec(num2hex(single(pi))))
and add zeros on the left for having indeed 32 bits ...
Titus
Hi Titus,
I was actually looking for conversion of a matrix of real numbers into single precision binary. Any idea?
So, did you try the above code? It works for matrices also.
yes it works, thank you !!!

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Aparna
Aparna le 9 Nov 2011

0 votes

hey actually it works i guess! thank you daniel and titus
This will convert a single precision float to 32 bit binary using IEEE 754 format where;
  • s is the sign bit (bit 31)
  • e is the exponent (bits 30 to 23)
  • m is the mantissa (bits 22 to 0)
% a is the float number
% b is the 32 bit binary converted number
b = padarray(hexToBinaryVector(num2hex(single(a)))',32-length(hexToBinaryVector(num2hex(single(a)))'),'pre')';
sign = b(1)
exp = b(2:9)
mantissa = b(10:32)

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