zlarnv.c

SuperLU is a general purpose library for the direct solution of large, sparse, nonsymmetric systems

#include "f2c.h"

/* Subroutine */ int zlarnv_(integer *idist, integer *iseed, integer *n, 
	doublecomplex *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   
    =======   

    ZLARNV 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*16 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, i__4, i__5;
    doublereal d__1, d__2;
    doublecomplex z__1, z__2, z__3;
    /* Builtin functions */
    double log(doublereal), sqrt(doublereal);
    void z_exp(doublecomplex *, doublecomplex *);
    /* Local variables */
    static integer i;
    static doublereal u[128];
    static integer il, iv;
    extern /* Subroutine */ int dlaruv_(integer *, integer *, doublereal *);


#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);

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

	i__2 = il << 1;
	dlaruv_(&ISEED(1), &i__2, u);

	if (*idist == 1) {

/*           Copy generated numbers */

	    i__2 = il;
	    for (i = 1; i <= il; ++i) {
		i__3 = iv + i - 1;
		i__4 = (i << 1) - 2;
		i__5 = (i << 1) - 1;
		z__1.r = U((i<<1)-2), z__1.i = U((i<<1)-1);
		X(iv+i-1).r = z__1.r, X(iv+i-1).i = z__1.i;
/* L10: */
	    }
	} else if (*idist == 2) {

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

	    i__2 = il;
	    for (i = 1; i <= il; ++i) {
		i__3 = iv + i - 1;
		d__1 = U((i << 1) - 2) * 2. - 1.;
		d__2 = U((i << 1) - 1) * 2. - 1.;
		z__1.r = d__1, z__1.i = d__2;
		X(iv+i-1).r = z__1.r, X(iv+i-1).i = z__1.i;
/* L20: */
	    }
	} else if (*idist == 3) {

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

	    i__2 = il;
	    for (i = 1; i <= il; ++i) {
		i__3 = iv + i - 1;
		d__1 = sqrt(log(U((i << 1) - 2)) * -2.);
		d__2 = U((i << 1) - 1) * 6.2831853071795864769252867663;
		z__3.r = 0., z__3.i = d__2;
		z_exp(&z__2, &z__3);
		z__1.r = d__1 * z__2.r, z__1.i = d__1 * z__2.i;
		X(iv+i-1).r = z__1.r, X(iv+i-1).i = z__1.i;
/* L30: */
	    }
	} else if (*idist == 4) {

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

	    i__2 = il;
	    for (i = 1; i <= il; ++i) {
		i__3 = iv + i - 1;
		d__1 = sqrt(U((i << 1) - 2));
		d__2 = U((i << 1) - 1) * 6.2831853071795864769252867663;
		z__3.r = 0., z__3.i = d__2;
		z_exp(&z__2, &z__3);
		z__1.r = d__1 * z__2.r, z__1.i = d__1 * z__2.i;
		X(iv+i-1).r = z__1.r, X(iv+i-1).i = z__1.i;
/* L40: */
	    }
	} else if (*idist == 5) {

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

	    i__2 = il;
	    for (i = 1; i <= il; ++i) {
		i__3 = iv + i - 1;
		d__1 = U((i << 1) - 1) * 6.2831853071795864769252867663;
		z__2.r = 0., z__2.i = d__1;
		z_exp(&z__1, &z__2);
		X(iv+i-1).r = z__1.r, X(iv+i-1).i = z__1.i;
/* L50: */
	    }
	}
/* L60: */
    }
    return 0;

/*     End of ZLARNV */

} /* zlarnv_ */