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drand48.3c (2010 09)

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drand48(3C) drand48(3C)
NAME
drand48( ), erand48( ), lrand48( ), nrand48( ), mrand48( ), jrand48( ), srand48( ), seed48( ), lcong48( ) - gen-
erate uniformly distributed pseudo-random numbers
SYNOPSIS
#include <stdlib.h>
double drand48(void);
double erand48(unsigned short int xsubi[3]);
long int lrand48(void);
long int nrand48(unsigned short int xsubi[3]);
long int mrand48(void);
long int jrand48(unsigned short int xsubi[3]);
void srand48(long int seedval);
unsigned short int *seed48(unsigned short int seed16v[3]);
void lcong48(unsigned short int param[7]);
Obsolescent Interfaces
int drand48_r(struct drand48_data *dp, double *randval);
int erand48_r(
unsigned short int xsubi[3],
struct drand48_data *dp,
double *randval);
int lrand48_r(struct drand48_data *dp, long int *randval);
int nrand48_r(
unsigned short int xsubi[3],
struct drand48_data *dp,
long int *randval);
int mrand48_r(struct drand48_data *dp, long int *randval);
int jrand48_r(
unsigned short int xsubi[3],
struct drand48_data *dp,
long int *randval);
int srand48_r(long int seedval, struct drand48_data *dp);
int seed48_r(unsigned short int seed16v[3], struct drand48_data *dp);
int lcong48_r(unsigned short int param[7], struct drand48_data *dp);
DESCRIPTION
This family of functions generates pseudo-random numbers using the well-known linear congruential
algorithm and 48-bit integer arithmetic.
In the following description, the formal mathematical notation [low,high) indicates an interval including
low but not including high.
drand48() and erand48() return nonnegative double-precision floating-point values uniformly distri-
buted over the interval [0.0,1.0).
lrand48() and nrand48() return nonnegative long integers uniformly distributed over the interval
[0,2ˆ31).
mrand48() and jrand48() return signed long integers uniformly distributed over the interval
[−2ˆ31,2ˆ31).
srand48(), seed48(), and lcong48() are initialization entry points, one of which should be
invoked before either drand48(), lrand48(),ormrand48() is called. (Although it is not recom-
mended practice, constant default initializer values are supplied automatically if drand48(),
lrand48(),ormrand48() is called without a prior call to an initialization entry point.) erand48(),
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1

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