irand(3f) [bsd man page]

RAND(3F)																  RAND(3F)

NAME

       rand, drand, irand - return random values

SYNOPSIS

       function irand (iflag)

       function rand (iflag)

       double precision function drand (iflag)

DESCRIPTION

       The newer random(3f) should be used in new applications; rand remains for compatibilty.

       These  functions  use  rand(3C)	to generate sequences of random numbers.  If iflag is '1', the generator is restarted and the first random
       value is returned.  If iflag is otherwise non-zero, it is used as a new seed for the random number generator,  and  the	first  new  random
       value is returned.

       Irand returns positive integers in the range 0 through 2147483647.  Rand and drand return values in the range 0. through 1.0 .

FILES

       /usr/lib/libF77.a

SEE ALSO

       random(3F), rand(3C)

BUGS

       The  algorithm  returns a 15 bit quantity on the PDP11; a 31 bit quantity on the VAX.  Irand on the PDP11 calls rand(3C) twice to form a 31
       bit quantity, but bit 15 will always be 0.

4.2 Berkeley Distribution					   May 15, 1985 							  RAND(3F)

RAND(3) 						   BSD Library Functions Manual 						   RAND(3)

NAME

     rand, rand_r, srand, sranddev -- bad random number generator

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <stdlib.h>

     int
     rand(void);

     int
     rand_r(unsigned *seed);

     void
     srand(unsigned seed);

     void
     sranddev(void);

DESCRIPTION

     These interfaces are obsoleted by arc4random(3).

     The rand() function computes a sequence of pseudo-random integers in the range of 0 to RAND_MAX (as defined by the header file <stdlib.h>).

     The srand() function sets its argument seed as the seed for a new sequence of pseudo-random numbers to be returned by rand().  These
     sequences are repeatable by calling srand() with the same seed value.

     If no seed value is provided, the functions are automatically seeded with a value of 1.

     The sranddev() function initializes a seed, using the random(4) random number device which returns good random numbers.  However, the rand()
     function still remains unsuitable for cryptographic use.

     The rand_r() function provides the same functionality as rand().  A pointer to the context value seed must be supplied by the caller.

SEE ALSO

     arc4random(3), random(3), random(4)

STANDARDS

     The rand() and srand() functions conform to ISO/IEC 9899:1990 (``ISO C90'').

     The rand_r() function is as proposed in the POSIX.4a Draft #6 document.

BSD
								   May 25, 1999 							       BSD