blank.gif (43 bytes)

Church Of The
Swimming Elephant

3.6 Floating-point Connected: An Internet Encyclopedia
3.6 Floating-point

Up: Connected: An Internet Encyclopedia
Up: Requests For Comments
Up: RFC 1832
Prev: 3.5 Hyper Integer and Unsigned Hyper Integer
Next: 3.7 Double-precision Floating-point

3.6 Floating-point

3.6 Floating-point

The standard defines the floating-point data type "float" (32 bits or 4 bytes). The encoding used is the IEEE standard for normalized single-precision floating-point numbers [3]. The following three fields describe the single-precision floating-point number:

      S: The sign of the number.  Values 0 and 1 represent positive and
         negative, respectively.  One bit.

      E: The exponent of the number, base 2.  8 bits are devoted to this
         field.  The exponent is biased by 127.

      F: The fractional part of the number's mantissa, base 2.  23 bits
         are devoted to this field.

Therefore, the floating-point number is described by:

         (-1)**S * 2**(E-Bias) * 1.F

It is declared as follows:

         float identifier;

         |byte 0 |byte 1 |byte 2 |byte 3 |              SINGLE-PRECISION
         S|   E   |           F          |         FLOATING-POINT NUMBER
         1|<- 8 ->|<-------23 bits------>|
         <------------32 bits------------>

Just as the most and least significant bytes of a number are 0 and 3, the most and least significant bits of a single-precision floating- point number are 0 and 31. The beginning bit (and most significant bit) offsets of S, E, and F are 0, 1, and 9, respectively. Note that these numbers refer to the mathematical positions of the bits, and NOT to their actual physical locations (which vary from medium to medium).

The IEEE specifications should be consulted concerning the encoding for signed zero, signed infinity (overflow), and denormalized numbers (underflow) [3]. According to IEEE specifications, the "NaN" (not a number) is system dependent and should not be interpreted within XDR as anything other than "NaN".

Next: 3.7 Double-precision Floating-point

Connected: An Internet Encyclopedia
3.6 Floating-point


Protect yourself from cyberstalkers, identity thieves, and those who would snoop on you.
Stop spam from invading your inbox without losing the mail you want. We give you more control over your e-mail than any other service.
Block popups, ads, and malicious scripts while you surf the net through our anonymous proxies.
Participate in Usenet, host your web files, easily send anonymous messages, and more, much more.
All private, all encrypted, all secure, all in an easy to use service, and all for only $5.95 a month!

Service Details

Have you gone to church today?
All pages ©1999, 2000, 2001, 2002, 2003 Church of the Swimming Elephant unless otherwise stated
Church of the Swimming Elephant©1999, 2000, 2001, 2002, 2003 is a wholly owned subsidiary of Packetderm, LLC.

Packetderm, LLC
210 Park Ave #308
Worcester, MA 01609