## Linux and UNIX Man Pages

Test Your Knowledge in Computers #237
Difficulty: Easy
Paul Baran was the first to build a theoretical model for communication using packet switching.
True or False?

# drand(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

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)```

## Check Out this Related Man Page

```rand(3UCB)					     SunOS/BSD Compatibility Library Functions						rand(3UCB)

NAME
rand, srand - simple random number generator

SYNOPSIS
/usr/ucb/cc [ flag ... ] file ...

int rand();

int srand(seed)
unsigned seed;

DESCRIPTION
rand()  uses a multiplicative congruential random number generator with period 2^32 to return successive pseudo-random numbers in the range
from 0 to 2^31 -1.

srand() can be called at any time to reset the random-number generator to a random starting point. The generator is initially seeded with a
value of 1.

cc(1B), drand48(3C), rand(3C), random(3C)

NOTES
Use of these interfaces should be restricted to only applications written on BSD platforms.  Use of these interfaces with any of the system
libraries or in multi-thread applications is unsupported.

The spectral properties of rand() leave a great deal to be desired. drand48(3C) and random(3C) provide much better, though more	elaborate,
random-number generators.

The low bits of the numbers generated are not very random; use the middle bits. In particular the lowest bit alternates between 0 and 1.

SunOS 5.11							    30 Oct 2007 							rand(3UCB)```

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