#include "f2c.h"

/* Subroutine */ int dlarnv_(integer *idist, integer *iseed, integer *n, 

	doublereal *x)

{

/*  -- LAPACK auxiliary routine (version 2.0) --   

       Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,   

       Courant Institute, Argonne National Lab, and Rice University   

       September 30, 1994   

    Purpose   

    =======   

    DLARNV 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) DOUBLE PRECISION array, dimension (N)   

            The generated random numbers.   

    Further Details   

    ===============   

    This routine calls the auxiliary routine DLARUV 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.   

    ===================================================================== 

   Parameter adjustments   

       Function Body */

    /* System generated locals */

    integer i__1, i__2, i__3;

    /* Builtin functions */

    double log(doublereal), sqrt(doublereal), cos(doublereal);

    /* Local variables */

    static integer i;

    static doublereal u[128];

    static integer il, iv;

    extern /* Subroutine */ int dlaruv_(integer *, integer *, doublereal *);

    static integer il2;

#define U(I) u[(I)]

#define X(I) x[(I)-1]

#define ISEED(I) iseed[(I)-1]

    i__1 = *n;

    for (iv = 1; iv <= *n; iv += 64) {

/* Computing MIN */

	i__2 = 64, i__3 = *n - iv + 1;

	il = min(i__2,i__3);

	if (*idist == 3) {

	    il2 = il << 1;

	} else {

	    il2 = il;

	}

/*        Call DLARUV to generate IL2 numbers from a uniform (0,1)   

          distribution (IL2 <= LV) */

	dlaruv_(&ISEED(1), &il2, u);

	if (*idist == 1) {

/*           Copy generated numbers */

	    i__2 = il;

	    for (i = 1; i <= il; ++i) {

		X(iv + i - 1) = U(i - 1);

/* L10: */

	    }

	} else if (*idist == 2) {

/*           Convert generated numbers to uniform (-1,1) distribut

ion */

	    i__2 = il;

	    for (i = 1; i <= il; ++i) {

		X(iv + i - 1) = U(i - 1) * 2. - 1.;

/* L20: */

	    }

	} else if (*idist == 3) {

/*           Convert generated numbers to normal (0,1) distributio

n */

	    i__2 = il;

	    for (i = 1; i <= il; ++i) {

		X(iv + i - 1) = sqrt(log(U((i << 1) - 2)) * -2.) * cos(U((i <<

			 1) - 1) * 6.2831853071795864769252867663);

/* L30: */

	    }

	}

/* L40: */

    }

    return 0;

/*     End of DLARNV */

} /* dlarnv_ */