#include "blaswrap.h"
/*  -- translated by f2c (version 19990503).
   You must link the resulting object file with the libraries:
	-lf2c -lm   (in that order)
*/

#include "f2c.h"

/* Table of constant values */

static complex c_b1 = {0.f,0.f};
static complex c_b2 = {1.f,0.f};
static integer c__1 = 1;

/* Subroutine */ int cstt21_(integer *n, integer *kband, real *ad, real *ae, 
	real *sd, real *se, complex *u, integer *ldu, complex *work, real *
	rwork, real *result)
{
    /* System generated locals */
    integer u_dim1, u_offset, i__1, i__2, i__3;
    real r__1, r__2, r__3;
    complex q__1, q__2;

    /* Local variables */
    extern /* Subroutine */ int cher_(char *, integer *, real *, complex *, 
	    integer *, complex *, integer *);
    static real unfl;
    extern /* Subroutine */ int cher2_(char *, integer *, complex *, complex *
	    , integer *, complex *, integer *, complex *, integer *);
    static real temp1, temp2;
    static integer j;
    extern /* Subroutine */ int cgemm_(char *, char *, integer *, integer *, 
	    integer *, complex *, complex *, integer *, complex *, integer *, 
	    complex *, complex *, integer *);
    static real anorm, wnorm;
    extern doublereal clange_(char *, integer *, integer *, complex *, 
	    integer *, real *), clanhe_(char *, char *, integer *, 
	    complex *, integer *, real *), slamch_(char *);
    extern /* Subroutine */ int claset_(char *, integer *, integer *, complex 
	    *, complex *, complex *, integer *);
    static real ulp;


#define u_subscr(a_1,a_2) (a_2)*u_dim1 + a_1
#define u_ref(a_1,a_2) u[u_subscr(a_1,a_2)]


/*  -- LAPACK test routine (version 3.0) --   
       Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,   
       Courant Institute, Argonne National Lab, and Rice University   
       September 30, 1994   


    Purpose   
    =======   

    CSTT21  checks a decomposition of the form   

       A = U S U*   

    where * means conjugate transpose, A is real symmetric tridiagonal,   
    U is unitary, and S is real and diagonal (if KBAND=0) or symmetric   
    tridiagonal (if KBAND=1).  Two tests are performed:   

       RESULT(1) = | A - U S U* | / ( |A| n ulp )   

       RESULT(2) = | I - UU* | / ( n ulp )   

    Arguments   
    =========   

    N       (input) INTEGER   
            The size of the matrix.  If it is zero, CSTT21 does nothing.   
            It must be at least zero.   

    KBAND   (input) INTEGER   
            The bandwidth of the matrix S.  It may only be zero or one.   
            If zero, then S is diagonal, and SE is not referenced.  If   
            one, then S is symmetric tri-diagonal.   

    AD      (input) REAL array, dimension (N)   
            The diagonal of the original (unfactored) matrix A.  A is   
            assumed to be real symmetric tridiagonal.   

    AE      (input) REAL array, dimension (N-1)   
            The off-diagonal of the original (unfactored) matrix A.  A   
            is assumed to be symmetric tridiagonal.  AE(1) is the (1,2)   
            and (2,1) element, AE(2) is the (2,3) and (3,2) element, etc.   

    SD      (input) REAL array, dimension (N)   
            The diagonal of the real (symmetric tri-) diagonal matrix S.   

    SE      (input) REAL array, dimension (N-1)   
            The off-diagonal of the (symmetric tri-) diagonal matrix S.   
            Not referenced if KBSND=0.  If KBAND=1, then AE(1) is the   
            (1,2) and (2,1) element, SE(2) is the (2,3) and (3,2)   
            element, etc.   

    U       (input) COMPLEX array, dimension (LDU, N)   
            The unitary matrix in the decomposition.   

    LDU     (input) INTEGER   
            The leading dimension of U.  LDU must be at least N.   

    WORK    (workspace) COMPLEX array, dimension (N**2)   

    RWORK   (workspace) REAL array, dimension (N)   

    RESULT  (output) REAL array, dimension (2)   
            The values computed by the two tests described above.  The   
            values are currently limited to 1/ulp, to avoid overflow.   
            RESULT(1) is always modified.   

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


       1)      Constants   

       Parameter adjustments */
    --ad;
    --ae;
    --sd;
    --se;
    u_dim1 = *ldu;
    u_offset = 1 + u_dim1 * 1;
    u -= u_offset;
    --work;
    --rwork;
    --result;

    /* Function Body */
    result[1] = 0.f;
    result[2] = 0.f;
    if (*n <= 0) {
	return 0;
    }

    unfl = slamch_("Safe minimum");
    ulp = slamch_("Precision");

/*     Do Test 1   

       Copy A & Compute its 1-Norm: */

    claset_("Full", n, n, &c_b1, &c_b1, &work[1], n);

    anorm = 0.f;
    temp1 = 0.f;

    i__1 = *n - 1;
    for (j = 1; j <= i__1; ++j) {
	i__2 = (*n + 1) * (j - 1) + 1;
	i__3 = j;
	work[i__2].r = ad[i__3], work[i__2].i = 0.f;
	i__2 = (*n + 1) * (j - 1) + 2;
	i__3 = j;
	work[i__2].r = ae[i__3], work[i__2].i = 0.f;
	temp2 = (r__1 = ae[j], dabs(r__1));
/* Computing MAX */
	r__2 = anorm, r__3 = (r__1 = ad[j], dabs(r__1)) + temp1 + temp2;
	anorm = dmax(r__2,r__3);
	temp1 = temp2;
/* L10: */
    }

/* Computing 2nd power */
    i__2 = *n;
    i__1 = i__2 * i__2;
    i__3 = *n;
    work[i__1].r = ad[i__3], work[i__1].i = 0.f;
/* Computing MAX */
    r__2 = anorm, r__3 = (r__1 = ad[*n], dabs(r__1)) + temp1, r__2 = max(r__2,
	    r__3);
    anorm = dmax(r__2,unfl);

/*     Norm of A - USU* */

    i__1 = *n;
    for (j = 1; j <= i__1; ++j) {
	r__1 = -sd[j];
	cher_("L", n, &r__1, &u_ref(1, j), &c__1, &work[1], n);
/* L20: */
    }

    if (*n > 1 && *kband == 1) {
	i__1 = *n - 1;
	for (j = 1; j <= i__1; ++j) {
	    i__2 = j;
	    q__2.r = se[i__2], q__2.i = 0.f;
	    q__1.r = -q__2.r, q__1.i = -q__2.i;
	    cher2_("L", n, &q__1, &u_ref(1, j), &c__1, &u_ref(1, j + 1), &
		    c__1, &work[1], n);
/* L30: */
	}
    }

    wnorm = clanhe_("1", "L", n, &work[1], n, &rwork[1])
	    ;

    if (anorm > wnorm) {
	result[1] = wnorm / anorm / (*n * ulp);
    } else {
	if (anorm < 1.f) {
/* Computing MIN */
	    r__1 = wnorm, r__2 = *n * anorm;
	    result[1] = dmin(r__1,r__2) / anorm / (*n * ulp);
	} else {
/* Computing MIN */
	    r__1 = wnorm / anorm, r__2 = (real) (*n);
	    result[1] = dmin(r__1,r__2) / (*n * ulp);
	}
    }

/*     Do Test 2   

       Compute  UU* - I */

    cgemm_("N", "C", n, n, n, &c_b2, &u[u_offset], ldu, &u[u_offset], ldu, &
	    c_b1, &work[1], n);

    i__1 = *n;
    for (j = 1; j <= i__1; ++j) {
	i__2 = (*n + 1) * (j - 1) + 1;
	i__3 = (*n + 1) * (j - 1) + 1;
	q__1.r = work[i__3].r - 1.f, q__1.i = work[i__3].i + 0.f;
	work[i__2].r = q__1.r, work[i__2].i = q__1.i;
/* L40: */
    }

/* Computing MIN */
    r__1 = (real) (*n), r__2 = clange_("1", n, n, &work[1], n, &rwork[1]);
    result[2] = dmin(r__1,r__2) / (*n * ulp);

    return 0;

/*     End of CSTT21 */

} /* cstt21_ */

#undef u_ref
#undef u_subscr


