MATLAB: Is it possible to have a function that will convert from floating point to IEEE hexadecimal

MATLAB

Add a function that will convert from floating point to IEEE hexadecimal. You currently have an IEEE hexadecimal to floating point conversion function (hex2num). It would be very helpful if you supported its compliment, ie. floating point to IEEE hexadecimal. Using the 'format hex' statement won't work since I need to have access to the bits.

Best Answer

This enhancement has been made for Release 14 (R14). For previous product releases, read below for any possible workarounds:

You can download a file, NUM2IEEE, which computes the bits in the IEEE representation of a floating-point number, from the following location:

http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?objectId=2996&objectType=FILE

Related Solutions

MATLAB: How to convert an IEEE floating point number to a floating point number which has a specified number of exponent bits and mantissa bits using the Fixed Point Blockset 3.1 (R12.1)

Using the Fixed Point Blockset function NUM2FIXPT, any value stored in an IEEE double can be quantized to the value it would have with fewer mantissa bits and fewer exponent bits. For example,

   v = num2fixpt( pi, float(9,4) )
 v =
      3.1250

However, it should be noted that the returned results are still stored in a double.

   whos
    Name      Size           Bytes  Class
    v         1x1                8  double array

Using the hex format, it can be seen that most of the bits have been set to zero.

format hex
v
 v =
     4009000000000000

However, it is important to note that NUM2FIXPT only quantizes the current value. If you manipulate the quantized result, then the result will have the range and precision of an IEEE double.

For example the following uses up most of the bits in a double:

    v/3
 ans =
     1.04166666666667

To perform calculations at the lower precision, lots of calls to NUM2FIXPT would have to be inserted at the appropriate places. For example:

num2fixpt( v/3, float(9,4) )
 ans =
     1.06250000000000

MATLAB: Floating point to 16 bit hexadecimal

You can use this file exchange submission. It will convert your number to 16-bit half precision format. But instead of returning as a string, it will return the equivalent uint16 MATLAB object. To get binary string, you can do this,

halfPrecisionNumber = halfprecision(1.2);  % halfprecision() is provided in the file exchange package.
halfPrecisionString = dec2bin(halfPrecisionNumber, 16);

In case you face the following error on running the package

"Floating point bit pattern is not IEEE 754"

you can try following

Open halfprecision.c file.
Add following to include section

#include <stdint.h>

Replace 4 #define with the following macros

#define INT16_TYPE int16_t 
#define UINT16_TYPE uint16_t 
#define INT32_TYPE int32_t 
#define UINT32_TYPE uint32_t

Run mex halfprecision.c.

Best Answer

Related Solutions

MATLAB: How to convert an IEEE floating point number to a floating point number which has a specified number of exponent bits and mantissa bits using the Fixed Point Blockset 3.1 (R12.1)

MATLAB: Floating point to 16 bit hexadecimal

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