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

/* Subroutine */ int clargv_(integer *n, complex *x, integer *incx, complex *
	y, integer *incy, real *c__, integer *incc)
{
/*  -- LAPACK auxiliary routine (version 3.0) --   
       Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,   
       Courant Institute, Argonne National Lab, and Rice University   
       June 30, 1999   


    Purpose   
    =======   

    CLARGV generates a vector of complex plane rotations with real   
    cosines, determined by elements of the complex vectors x and y.   
    For i = 1,2,...,n   

       (        c(i)   s(i) ) ( x(i) ) = ( r(i) )   
       ( -conjg(s(i))  c(i) ) ( y(i) ) = (   0  )   

       where c(i)**2 + ABS(s(i))**2 = 1   

    The following conventions are used (these are the same as in CLARTG,   
    but differ from the BLAS1 routine CROTG):   
       If y(i)=0, then c(i)=1 and s(i)=0.   
       If x(i)=0, then c(i)=0 and s(i) is chosen so that r(i) is real.   

    Arguments   
    =========   

    N       (input) INTEGER   
            The number of plane rotations to be generated.   

    X       (input/output) COMPLEX array, dimension (1+(N-1)*INCX)   
            On entry, the vector x.   
            On exit, x(i) is overwritten by r(i), for i = 1,...,n.   

    INCX    (input) INTEGER   
            The increment between elements of X. INCX > 0.   

    Y       (input/output) COMPLEX array, dimension (1+(N-1)*INCY)   
            On entry, the vector y.   
            On exit, the sines of the plane rotations.   

    INCY    (input) INTEGER   
            The increment between elements of Y. INCY > 0.   

    C       (output) REAL array, dimension (1+(N-1)*INCC)   
            The cosines of the plane rotations.   

    INCC    (input) INTEGER   
            The increment between elements of C. INCC > 0.   

    Further Details   
    ======= =======   

    6-6-96 - Modified with a new algorithm by W. Kahan and J. Demmel   

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

       Parameter adjustments */
    /* Initialized data */
    static logical first = TRUE_;
    /* System generated locals */
    integer i__1, i__2;
    real r__1, r__2, r__3, r__4, r__5, r__6, r__7, r__8, r__9, r__10;
    complex q__1, q__2, q__3;
    /* Builtin functions */
    double log(doublereal), pow_ri(real *, integer *), r_imag(complex *), 
	    sqrt(doublereal);
    void r_cnjg(complex *, complex *);
    /* Local variables */
    static real d__;
    static complex f, g;
    static integer i__, j;
    static complex r__;
    static real scale;
    static integer count;
    static real f2, g2, safmn2, safmx2;
    extern doublereal slapy2_(real *, real *);
    static integer ic;
    static real di;
    static complex ff;
    static real cs, dr;
    static complex fs, gs;
    static integer ix, iy;
    static complex sn;
    extern doublereal slamch_(char *);
    static real safmin, f2s, g2s, eps;

    --c__;
    --y;
    --x;

    /* Function Body */

    if (first) {
	first = FALSE_;
	safmin = slamch_("S");
	eps = slamch_("E");
	r__1 = slamch_("B");
	i__1 = (integer) (log(safmin / eps) / log(slamch_("B")) / 
		2.f);
	safmn2 = pow_ri(&r__1, &i__1);
	safmx2 = 1.f / safmn2;
    }
    ix = 1;
    iy = 1;
    ic = 1;
    i__1 = *n;
    for (i__ = 1; i__ <= i__1; ++i__) {
	i__2 = ix;
	f.r = x[i__2].r, f.i = x[i__2].i;
	i__2 = iy;
	g.r = y[i__2].r, g.i = y[i__2].i;

/*        Use identical algorithm as in CLARTG   

   Computing MAX   
   Computing MAX */
	r__7 = (r__1 = f.r, dabs(r__1)), r__8 = (r__2 = r_imag(&f), dabs(r__2)
		);
/* Computing MAX */
	r__9 = (r__3 = g.r, dabs(r__3)), r__10 = (r__4 = r_imag(&g), dabs(
		r__4));
	r__5 = dmax(r__7,r__8), r__6 = dmax(r__9,r__10);
	scale = dmax(r__5,r__6);
	fs.r = f.r, fs.i = f.i;
	gs.r = g.r, gs.i = g.i;
	count = 0;
	if (scale >= safmx2) {
L10:
	    ++count;
	    q__1.r = safmn2 * fs.r, q__1.i = safmn2 * fs.i;
	    fs.r = q__1.r, fs.i = q__1.i;
	    q__1.r = safmn2 * gs.r, q__1.i = safmn2 * gs.i;
	    gs.r = q__1.r, gs.i = q__1.i;
	    scale *= safmn2;
	    if (scale >= safmx2) {
		goto L10;
	    }
	} else if (scale <= safmn2) {
	    if (g.r == 0.f && g.i == 0.f) {
		cs = 1.f;
		sn.r = 0.f, sn.i = 0.f;
		r__.r = f.r, r__.i = f.i;
		goto L50;
	    }
L20:
	    --count;
	    q__1.r = safmx2 * fs.r, q__1.i = safmx2 * fs.i;
	    fs.r = q__1.r, fs.i = q__1.i;
	    q__1.r = safmx2 * gs.r, q__1.i = safmx2 * gs.i;
	    gs.r = q__1.r, gs.i = q__1.i;
	    scale *= safmx2;
	    if (scale <= safmn2) {
		goto L20;
	    }
	}
/* Computing 2nd power */
	r__1 = fs.r;
/* Computing 2nd power */
	r__2 = r_imag(&fs);
	f2 = r__1 * r__1 + r__2 * r__2;
/* Computing 2nd power */
	r__1 = gs.r;
/* Computing 2nd power */
	r__2 = r_imag(&gs);
	g2 = r__1 * r__1 + r__2 * r__2;
	if (f2 <= dmax(g2,1.f) * safmin) {

/*           This is a rare case: F is very small. */

	    if (f.r == 0.f && f.i == 0.f) {
		cs = 0.f;
		r__2 = g.r;
		r__3 = r_imag(&g);
		r__1 = slapy2_(&r__2, &r__3);
		r__.r = r__1, r__.i = 0.f;
/*              Do complex/real division explicitly with two real   
                divisions */
		r__1 = gs.r;
		r__2 = r_imag(&gs);
		d__ = slapy2_(&r__1, &r__2);
		r__1 = gs.r / d__;
		r__2 = -r_imag(&gs) / d__;
		q__1.r = r__1, q__1.i = r__2;
		sn.r = q__1.r, sn.i = q__1.i;
		goto L50;
	    }
	    r__1 = fs.r;
	    r__2 = r_imag(&fs);
	    f2s = slapy2_(&r__1, &r__2);
/*           G2 and G2S are accurate   
             G2 is at least SAFMIN, and G2S is at least SAFMN2 */
	    g2s = sqrt(g2);
/*           Error in CS from underflow in F2S is at most   
             UNFL / SAFMN2 .lt. sqrt(UNFL*EPS) .lt. EPS   
             If MAX(G2,ONE)=G2, then F2 .lt. G2*SAFMIN,   
             and so CS .lt. sqrt(SAFMIN)   
             If MAX(G2,ONE)=ONE, then F2 .lt. SAFMIN   
             and so CS .lt. sqrt(SAFMIN)/SAFMN2 = sqrt(EPS)   
             Therefore, CS = F2S/G2S / sqrt( 1 + (F2S/G2S)**2 ) = F2S/G2S */
	    cs = f2s / g2s;
/*           Make sure abs(FF) = 1   
             Do complex/real division explicitly with 2 real divisions   
   Computing MAX */
	    r__3 = (r__1 = f.r, dabs(r__1)), r__4 = (r__2 = r_imag(&f), dabs(
		    r__2));
	    if (dmax(r__3,r__4) > 1.f) {
		r__1 = f.r;
		r__2 = r_imag(&f);
		d__ = slapy2_(&r__1, &r__2);
		r__1 = f.r / d__;
		r__2 = r_imag(&f) / d__;
		q__1.r = r__1, q__1.i = r__2;
		ff.r = q__1.r, ff.i = q__1.i;
	    } else {
		dr = safmx2 * f.r;
		di = safmx2 * r_imag(&f);
		d__ = slapy2_(&dr, &di);
		r__1 = dr / d__;
		r__2 = di / d__;
		q__1.r = r__1, q__1.i = r__2;
		ff.r = q__1.r, ff.i = q__1.i;
	    }
	    r__1 = gs.r / g2s;
	    r__2 = -r_imag(&gs) / g2s;
	    q__2.r = r__1, q__2.i = r__2;
	    q__1.r = ff.r * q__2.r - ff.i * q__2.i, q__1.i = ff.r * q__2.i + 
		    ff.i * q__2.r;
	    sn.r = q__1.r, sn.i = q__1.i;
	    q__2.r = cs * f.r, q__2.i = cs * f.i;
	    q__3.r = sn.r * g.r - sn.i * g.i, q__3.i = sn.r * g.i + sn.i * 
		    g.r;
	    q__1.r = q__2.r + q__3.r, q__1.i = q__2.i + q__3.i;
	    r__.r = q__1.r, r__.i = q__1.i;
	} else {

/*           This is the most common case.   
             Neither F2 nor F2/G2 are less than SAFMIN   
             F2S cannot overflow, and it is accurate */

	    f2s = sqrt(g2 / f2 + 1.f);
/*           Do the F2S(real)*FS(complex) multiply with two real   
             multiplies */
	    r__1 = f2s * fs.r;
	    r__2 = f2s * r_imag(&fs);
	    q__1.r = r__1, q__1.i = r__2;
	    r__.r = q__1.r, r__.i = q__1.i;
	    cs = 1.f / f2s;
	    d__ = f2 + g2;
/*           Do complex/real division explicitly with two real divisions */
	    r__1 = r__.r / d__;
	    r__2 = r_imag(&r__) / d__;
	    q__1.r = r__1, q__1.i = r__2;
	    sn.r = q__1.r, sn.i = q__1.i;
	    r_cnjg(&q__2, &gs);
	    q__1.r = sn.r * q__2.r - sn.i * q__2.i, q__1.i = sn.r * q__2.i + 
		    sn.i * q__2.r;
	    sn.r = q__1.r, sn.i = q__1.i;
	    if (count != 0) {
		if (count > 0) {
		    i__2 = count;
		    for (j = 1; j <= i__2; ++j) {
			q__1.r = safmx2 * r__.r, q__1.i = safmx2 * r__.i;
			r__.r = q__1.r, r__.i = q__1.i;
/* L30: */
		    }
		} else {
		    i__2 = -count;
		    for (j = 1; j <= i__2; ++j) {
			q__1.r = safmn2 * r__.r, q__1.i = safmn2 * r__.i;
			r__.r = q__1.r, r__.i = q__1.i;
/* L40: */
		    }
		}
	    }
	}
L50:
	c__[ic] = cs;
	i__2 = iy;
	y[i__2].r = sn.r, y[i__2].i = sn.i;
	i__2 = ix;
	x[i__2].r = r__.r, x[i__2].i = r__.i;
	ic += *incc;
	iy += *incy;
	ix += *incx;
/* L60: */
    }
    return 0;

/*     End of CLARGV */

} /* clargv_ */

