 LAPACK 3.11.0 LAPACK: Linear Algebra PACKage
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## ◆ dlarnd()

 double precision function dlarnd ( integer IDIST, integer, dimension( 4 ) ISEED )

DLARND

Purpose:
``` DLARND returns a random real number from a uniform or normal
distribution.```
Parameters
 [in] IDIST ``` IDIST is INTEGER Specifies the distribution of the random numbers: = 1: uniform (0,1) = 2: uniform (-1,1) = 3: normal (0,1)``` [in,out] ISEED ``` ISEED is INTEGER array, dimension (4) On entry, the seed of the random number generator; the array elements must be between 0 and 4095, and ISEED(4) must be odd. On exit, the seed is updated.```
Further Details:
```  This routine calls the auxiliary routine DLARAN to generate a random
real number from a uniform (0,1) distribution. The Box-Muller method
is used to transform numbers from a uniform to a normal distribution.```

Definition at line 72 of file dlarnd.f.

73*
74* -- LAPACK auxiliary routine --
75* -- LAPACK is a software package provided by Univ. of Tennessee, --
76* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
77*
78* .. Scalar Arguments ..
79 INTEGER IDIST
80* ..
81* .. Array Arguments ..
82 INTEGER ISEED( 4 )
83* ..
84*
85* =====================================================================
86*
87* .. Parameters ..
88 DOUBLE PRECISION ONE, TWO
89 parameter( one = 1.0d+0, two = 2.0d+0 )
90 DOUBLE PRECISION TWOPI
91 parameter( twopi = 6.28318530717958647692528676655900576839d+0 )
92* ..
93* .. Local Scalars ..
94 DOUBLE PRECISION T1, T2
95* ..
96* .. External Functions ..
97 DOUBLE PRECISION DLARAN
98 EXTERNAL dlaran
99* ..
100* .. Intrinsic Functions ..
101 INTRINSIC cos, log, sqrt
102* ..
103* .. Executable Statements ..
104*
105* Generate a real random number from a uniform (0,1) distribution
106*
107 t1 = dlaran( iseed )
108*
109 IF( idist.EQ.1 ) THEN
110*
111* uniform (0,1)
112*
113 dlarnd = t1
114 ELSE IF( idist.EQ.2 ) THEN
115*
116* uniform (-1,1)
117*
118 dlarnd = two*t1 - one
119 ELSE IF( idist.EQ.3 ) THEN
120*
121* normal (0,1)
122*
123 t2 = dlaran( iseed )
124 dlarnd = sqrt( -two*log( t1 ) )*cos( twopi*t2 )
125 END IF
126 RETURN
127*
128* End of DLARND
129*
double precision function dlaran(ISEED)
DLARAN
Definition: dlaran.f:67
double precision function dlarnd(IDIST, ISEED)
DLARND
Definition: dlarnd.f:73
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