#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 doublereal c_b5 = 0.;
static integer c__1 = 1;
static doublereal c_b19 = 1.;

/* Subroutine */ int dstt21_(integer *n, integer *kband, doublereal *ad, 
	doublereal *ae, doublereal *sd, doublereal *se, doublereal *u, 
	integer *ldu, doublereal *work, doublereal *result)
{
    /* System generated locals */
    integer u_dim1, u_offset, i__1;
    doublereal d__1, d__2, d__3;

    /* Local variables */
    static doublereal unfl;
    extern /* Subroutine */ int dsyr_(char *, integer *, doublereal *, 
	    doublereal *, integer *, doublereal *, integer *);
    static doublereal temp1, temp2;
    extern /* Subroutine */ int dsyr2_(char *, integer *, doublereal *, 
	    doublereal *, integer *, doublereal *, integer *, doublereal *, 
	    integer *);
    static integer j;
    extern /* Subroutine */ int dgemm_(char *, char *, integer *, integer *, 
	    integer *, doublereal *, doublereal *, integer *, doublereal *, 
	    integer *, doublereal *, doublereal *, integer *);
    static doublereal anorm, wnorm;
    extern doublereal dlamch_(char *), dlange_(char *, integer *, 
	    integer *, doublereal *, integer *, doublereal *);
    extern /* Subroutine */ int dlaset_(char *, integer *, integer *, 
	    doublereal *, doublereal *, doublereal *, integer *);
    extern doublereal dlansy_(char *, char *, integer *, doublereal *, 
	    integer *, doublereal *);
    static doublereal ulp;


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


/*  -- 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   
    =======   

    DSTT21 checks a decomposition of the form   

       A = U S U'   

    where ' means transpose, A is symmetric tridiagonal, U is orthogonal,   
    and S is 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, DSTT21 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) DOUBLE PRECISION array, dimension (N)   
            The diagonal of the original (unfactored) matrix A.  A is   
            assumed to be symmetric tridiagonal.   

    AE      (input) DOUBLE PRECISION 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) DOUBLE PRECISION array, dimension (N)   
            The diagonal of the (symmetric tri-) diagonal matrix S.   

    SE      (input) DOUBLE PRECISION 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) DOUBLE PRECISION array, dimension (LDU, N)   
            The orthogonal matrix in the decomposition.   

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

    WORK    (workspace) DOUBLE PRECISION array, dimension (N*(N+1))   

    RESULT  (output) DOUBLE PRECISION 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;
    --result;

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

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

/*     Do Test 1   

       Copy A & Compute its 1-Norm: */

    dlaset_("Full", n, n, &c_b5, &c_b5, &work[1], n);

    anorm = 0.;
    temp1 = 0.;

    i__1 = *n - 1;
    for (j = 1; j <= i__1; ++j) {
	work[(*n + 1) * (j - 1) + 1] = ad[j];
	work[(*n + 1) * (j - 1) + 2] = ae[j];
	temp2 = (d__1 = ae[j], abs(d__1));
/* Computing MAX */
	d__2 = anorm, d__3 = (d__1 = ad[j], abs(d__1)) + temp1 + temp2;
	anorm = max(d__2,d__3);
	temp1 = temp2;
/* L10: */
    }

/* Computing 2nd power */
    i__1 = *n;
    work[i__1 * i__1] = ad[*n];
/* Computing MAX */
    d__2 = anorm, d__3 = (d__1 = ad[*n], abs(d__1)) + temp1, d__2 = max(d__2,
	    d__3);
    anorm = max(d__2,unfl);

/*     Norm of A - USU' */

    i__1 = *n;
    for (j = 1; j <= i__1; ++j) {
	d__1 = -sd[j];
	dsyr_("L", n, &d__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) {
	    d__1 = -se[j];
	    dsyr2_("L", n, &d__1, &u_ref(1, j), &c__1, &u_ref(1, j + 1), &
		    c__1, &work[1], n);
/* L30: */
	}
    }

/* Computing 2nd power */
    i__1 = *n;
    wnorm = dlansy_("1", "L", n, &work[1], n, &work[i__1 * i__1 + 1]);

    if (anorm > wnorm) {
	result[1] = wnorm / anorm / (*n * ulp);
    } else {
	if (anorm < 1.) {
/* Computing MIN */
	    d__1 = wnorm, d__2 = *n * anorm;
	    result[1] = min(d__1,d__2) / anorm / (*n * ulp);
	} else {
/* Computing MIN */
	    d__1 = wnorm / anorm, d__2 = (doublereal) (*n);
	    result[1] = min(d__1,d__2) / (*n * ulp);
	}
    }

/*     Do Test 2   

       Compute  UU' - I */

    dgemm_("N", "C", n, n, n, &c_b19, &u[u_offset], ldu, &u[u_offset], ldu, &
	    c_b5, &work[1], n);

    i__1 = *n;
    for (j = 1; j <= i__1; ++j) {
	work[(*n + 1) * (j - 1) + 1] += -1.;
/* L40: */
    }

/* Computing MIN   
   Computing 2nd power */
    i__1 = *n;
    d__1 = (doublereal) (*n), d__2 = dlange_("1", n, n, &work[1], n, &work[
	    i__1 * i__1 + 1]);
    result[2] = min(d__1,d__2) / (*n * ulp);

    return 0;

/*     End of DSTT21 */

} /* dstt21_ */

#undef u_ref


