clarnv.c

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/* clarnv.f -- translated by f2c (version 20061008).
   You must link the resulting object file with libf2c:
        on Microsoft Windows system, link with libf2c.lib;
        on Linux or Unix systems, link with .../path/to/libf2c.a -lm
        or, if you install libf2c.a in a standard place, with -lf2c -lm
        -- in that order, at the end of the command line, as in
                cc *.o -lf2c -lm
        Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,

                http://www.netlib.org/f2c/libf2c.zip
*/

#include "f2c.h"
#include "blaswrap.h"

/* Subroutine */ int clarnv_(integer *idist, integer *iseed, integer *n, 
        complex *x)
{
    /* System generated locals */
    integer i__1, i__2, i__3, i__4, i__5;
    real r__1, r__2;
    complex q__1, q__2, q__3;

    /* Builtin functions */
    double log(doublereal), sqrt(doublereal);
    void c_exp(complex *, complex *);

    /* Local variables */
    integer i__;
    real u[128];
    integer il, iv;
    extern /* Subroutine */ int slaruv_(integer *, integer *, real *);


/*  -- LAPACK auxiliary routine (version 3.2) -- */
/*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/*     November 2006 */

/*     .. Scalar Arguments .. */
/*     .. */
/*     .. Array Arguments .. */
/*     .. */

/*  Purpose */
/*  ======= */

/*  CLARNV returns a vector of n random complex numbers from a uniform or */
/*  normal distribution. */

/*  Arguments */
/*  ========= */

/*  IDIST   (input) INTEGER */
/*          Specifies the distribution of the random numbers: */
/*          = 1:  real and imaginary parts each uniform (0,1) */
/*          = 2:  real and imaginary parts each uniform (-1,1) */
/*          = 3:  real and imaginary parts each normal (0,1) */
/*          = 4:  uniformly distributed on the disc abs(z) < 1 */
/*          = 5:  uniformly distributed on the circle abs(z) = 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) COMPLEX 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. */

/*  ===================================================================== */

/*     .. Parameters .. */
/*     .. */
/*     .. Local Scalars .. */
/*     .. */
/*     .. Local Arrays .. */
/*     .. */
/*     .. Intrinsic Functions .. */
/*     .. */
/*     .. External Subroutines .. */
/*     .. */
/*     .. Executable Statements .. */

    /* Parameter adjustments */
    --x;
    --iseed;

    /* Function Body */
    i__1 = *n;
    for (iv = 1; iv <= i__1; iv += 64) {
/* Computing MIN */
        i__2 = 64, i__3 = *n - iv + 1;
        il = min(i__2,i__3);

/*        Call SLARUV to generate 2*IL real numbers from a uniform (0,1) */
/*        distribution (2*IL <= LV) */

        i__2 = il << 1;
        slaruv_(&iseed[1], &i__2, u);

        if (*idist == 1) {

/*           Copy generated numbers */

            i__2 = il;
            for (i__ = 1; i__ <= i__2; ++i__) {
                i__3 = iv + i__ - 1;
                i__4 = (i__ << 1) - 2;
                i__5 = (i__ << 1) - 1;
                q__1.r = u[i__4], q__1.i = u[i__5];
                x[i__3].r = q__1.r, x[i__3].i = q__1.i;
/* L10: */
            }
        } else if (*idist == 2) {

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

            i__2 = il;
            for (i__ = 1; i__ <= i__2; ++i__) {
                i__3 = iv + i__ - 1;
                r__1 = u[(i__ << 1) - 2] * 2.f - 1.f;
                r__2 = u[(i__ << 1) - 1] * 2.f - 1.f;
                q__1.r = r__1, q__1.i = r__2;
                x[i__3].r = q__1.r, x[i__3].i = q__1.i;
/* L20: */
            }
        } else if (*idist == 3) {

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

            i__2 = il;
            for (i__ = 1; i__ <= i__2; ++i__) {
                i__3 = iv + i__ - 1;
                r__1 = sqrt(log(u[(i__ << 1) - 2]) * -2.f);
                r__2 = u[(i__ << 1) - 1] * 6.2831853071795864769252867663f;
                q__3.r = 0.f, q__3.i = r__2;
                c_exp(&q__2, &q__3);
                q__1.r = r__1 * q__2.r, q__1.i = r__1 * q__2.i;
                x[i__3].r = q__1.r, x[i__3].i = q__1.i;
/* L30: */
            }
        } else if (*idist == 4) {

/*           Convert generated numbers to complex numbers uniformly */
/*           distributed on the unit disk */

            i__2 = il;
            for (i__ = 1; i__ <= i__2; ++i__) {
                i__3 = iv + i__ - 1;
                r__1 = sqrt(u[(i__ << 1) - 2]);
                r__2 = u[(i__ << 1) - 1] * 6.2831853071795864769252867663f;
                q__3.r = 0.f, q__3.i = r__2;
                c_exp(&q__2, &q__3);
                q__1.r = r__1 * q__2.r, q__1.i = r__1 * q__2.i;
                x[i__3].r = q__1.r, x[i__3].i = q__1.i;
/* L40: */
            }
        } else if (*idist == 5) {

/*           Convert generated numbers to complex numbers uniformly */
/*           distributed on the unit circle */

            i__2 = il;
            for (i__ = 1; i__ <= i__2; ++i__) {
                i__3 = iv + i__ - 1;
                r__1 = u[(i__ << 1) - 1] * 6.2831853071795864769252867663f;
                q__2.r = 0.f, q__2.i = r__1;
                c_exp(&q__1, &q__2);
                x[i__3].r = q__1.r, x[i__3].i = q__1.i;
/* L50: */
            }
        }
/* L60: */
    }
    return 0;

/*     End of CLARNV */

} /* clarnv_ */