slarnv(3S)

NAME
     SLARNV - return a vector of n random real numbers from a uniform or
     normal distribution

SYNOPSIS
     SUBROUTINE SLARNV( IDIST, ISEED, N, X )

         INTEGER        IDIST, N

         INTEGER        ISEED( 4 )

         REAL           X( * )

IMPLEMENTATION
     These routines are part of the SCSL Scientific Library and can be loaded
     using either the -lscs or the -lscs_mp option.  The -lscs_mp option
     directs the linker to use the multi-processor version of the library.

     When linking to SCSL with -lscs or -lscs_mp, the default integer size is
     4 bytes (32 bits). Another version of SCSL is available in which integers
     are 8 bytes (64 bits).  This version allows the user access to larger
     memory sizes and helps when porting legacy Cray codes.  It can be loaded
     by using the -lscs_i8 option or the -lscs_i8_mp option. A program may use
     only one of the two versions; 4-byte integer and 8-byte integer library
     calls cannot be mixed.

PURPOSE
     SLARNV returns a vector of n random real numbers from a uniform or normal
     distribution.

ARGUMENTS
     IDIST   (input) INTEGER
             Specifies the distribution of the random numbers:
             = 1:  uniform (0,1)
             = 2:  uniform (-1,1)
             = 3:  normal (0,1)

     ISEED   (input/output) 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.

     N       (input) INTEGER
             The number of random numbers to be generated.

     X       (output) REAL array, dimension (N)
             The generated random numbers.

FURTHER DETAILS
     This routine calls the auxiliary routine SLARUV to generate random real
     numbers from a uniform (0,1) distribution, in batches of up to 128 using
     vectorisable code. The Box-Muller method is used to transform numbers
     from a uniform to a normal distribution.


SEE ALSO
     INTRO_LAPACK(3S), INTRO_SCSL(3S)

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