[1] : WordNet (r) 2.0

magic number
     n : the atomic number of an extra stable strongly bound atomic
         nucleus: 2, 8, 20, 28, 50, 82 or 126

[2] : Jargon File (4.3.1, 29 Jun 2001)

magic number n. unix/c; common 1. in source code, some non-obvious
   constant whose value is significant to the operation of a program and
   that is inserted inconspicuously in-line hardcoded, rather than
   expanded in by a symbol set by a commented `define'. magic numbers in
   this sense are bad style. 2. a number that encodes critical information
   used in an algorithm in some opaque way. the classic examples of these
   are the numbers used in hash or crc functions, or the coefficients in a
   linear congruential generator for pseudo-random numbers. this sense
   actually predates and was ancestral to the more common sense 1. 3.
   special data located at the beginning of a binary data file to indicate
   its type to a utility. under unix, the system and various applications
   programs especially the linker distinguish between types of executable
   file by looking for a magic number. once upon a time, these magic
   numbers were pdp-11 branch instructions that skipped over header data to
   the start of executable code; 0407, for example, was octal for `branch
   16 bytes relative'. many other kinds of files now have magic numbers
   somewhere; some magic numbers are, in fact, strings, like the `'
   at the beginning of a unix archive file or the `' leading postscript
   files. nowadays only a wizard knows the spells to create magic
   numbers. how do you choose a fresh magic number of your own? simple --
   you pick one at random. see? it's magic

   _the_ magic number, on the other hand, is 7+/-2. see "the magical
   number seven, plus or minus two: some limits on our capacity for
   processing information" by george miller, in the "psychological review"
   63:81-97 1956. this classic paper established the number of distinct
   items such as numeric digits that humans can hold in short-term
   memory. among other things, this strongly influenced the interface
   design of the phone system.


see also:
hardcoded wizard 

[3] : The Free On-line Dictionary of Computing (27 SEP 03)

magic number
     
         1. in source code, some non-obvious
        constant whose value is significant to the operation of a
        program and that is inserted inconspicuously in-line
        hard-coded, rather than expanded in by a symbol set by a
        commented "define".  magic numbers in this sense are bad
        style.
     
        2. a number that encodes critical information used in an
        algorithm in some opaque way.  the classic examples of these
        are the numbers used in hash or crc functions or the
        coefficients in a linear congruential generator for
        pseudo-random numbers.  this sense actually predates, and
        was ancestral to, the more common sense 1.
     
        3. special data located at the beginning of a binary data
        file to indicate its type to a utility.  under unix, the
        system and various applications programs especially the
        linker distinguish between types of executable file by
        looking for a magic number.  once upon a time, these magic
        numbers were pdp-11 branch instructions that skipped over
        header data to the start of executable code; 0407, for
        example, was octal for "branch 16 bytes relative".  nowadays
        only a wizard knows the spells to create magic numbers.  ms
        dos executables begin with the magic string "mz".
     
        the magic number, on the other hand, is 7+/-2.  the paper
        cited below established the number of distinct items such as
        numeric digits that humans can hold in short-term memory.
        among other things, this strongly influenced the interface
        design of the phone system.
     
        "the magical number seven, plus or minus two: some limits on
        our capacity for processing information", george miller, in
        the "psychological review" 63:81-97, 1956.
     
        jargon file
     
        2003-07-02
     
     
see also:
source code hard-coded algorithm hash crc linear congruential generator 
pseudo-random binary unix applications programs linker 
pdp-11 octal wizard ms dos jargon file 

Magic >> M Words
Magic, definition of term: Magic
magic_pag1.html

Number >> N Words
Number, definition of term: Number
number_pag1.html

Magic Realism >> M Words
Magic Realism, definition of term: Magic Realism
magic+realism_pag1.html

Magic Cookie >> M Words
Magic Cookie, definition of term: Magic Cookie
magic+cookie_pag1.html

Number Sign >> N Words
Number Sign, definition of term: Number Sign
number+sign_pag1.html

Magic Wand >> M Words
Magic Wand, definition of term: Magic Wand
magic+wand_pag1.html

Number Cruncher >> N Words
Number Cruncher, definition of term: Number Cruncher
number+cruncher_pag1.html

Mixed Number >> M Words
Mixed Number, definition of term: Mixed Number
mixed+number_pag1.html

Natural Number >> N Words
Natural Number, definition of term: Natural Number
natural+number_pag1.html

Mach Number >> M Words
Mach Number, definition of term: Mach Number
mach+number_pag1.html

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