.\" @(#)ran.3f 1.5 93/02/01 SMI; from UCB 4.2
.TH RAN 3F "07 July 1995"
.SH NAME
ran \- return a random number between 0 and 1
.SH SYNOPSIS
.\"
.IX ran "" \fLran\fR
.IX random values
.\"
.B real function ran (i)
.br
.B integer*4 i
.SH DESCRIPTION
Repeated calls to
.B ran
generate random numbers with a uniform distribution.
.\"
.SH NOTES
.\"
.PP
See
.BR lcrans (3m).
.PP
The range includes 0.0 and excludes 1.0.
The algorithm is a multiplicative, congruential type,
general random number generator.
In general, the value of
.B i
is set once during execution of the calling program.
The initial value of
.B i
should be a large odd integer.
Each call to
.B ran
returns the next random number in the sequence.
.PP
To get a different sequence of random numbers each
time you run the calling program,
you must set the argument
.B i
to a different initial value for each run.
.sp
Usage:
.sp .2
.br
.in +2
.nf
.ft 3
real  r, ran
integer*4 i
i = ...
     ...
r = ran(i)
.ft 1
.fi
.in -2
.sp
Example:
.sp .2
demo% 
.B "cat ran1.f"
.br
.B "* ran1.f" 
\        <-- 
.I Generate random numbers 
.br
.nf
.ft 3
	integer*4 i, n 
	real r(10) 
	i = 760013 
	do n = 1, 10 
		r(n) = ran ( i ) 
	end do 
	write ( *, "( 5 f11.6 )" ) r 
	end 
.ft 1
.fi
.br
demo% 
.B "f77 \-silent ran1.f"
.br
demo% 
.B a.out 
.br
.nf
   0.222058 0.299851 0.390777 0.607055 0.653188 
   0.060174 0.149466 0.444353 0.002982 0.976519
.fi
.br
demo% 
.SH FILES
.BR libF77.a 
.SH "SEE ALSO"
.BR lcrans, 
.BR addrans, 
and 
.BR shufrans
in the 
.I "Numerical Computation Guide"