#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 real c_b12 = 1.f;
static real c_b13 = 0.f;

/* Subroutine */ int sstt22_(integer *n, integer *m, integer *kband, real *ad,
	 real *ae, real *sd, real *se, real *u, integer *ldu, real *work, 
	integer *ldwork, real *result)
{
    /* System generated locals */
    integer u_dim1, u_offset, work_dim1, work_offset, i__1, i__2, i__3;
    real r__1, r__2, r__3, r__4, r__5;

    /* Local variables */
    static real aukj, unfl;
    static integer i__, j, k;
    extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *, 
	    integer *, real *, real *, integer *, real *, integer *, real *, 
	    real *, integer *);
    static real anorm, wnorm;
    extern doublereal slamch_(char *), slange_(char *, integer *, 
	    integer *, real *, integer *, real *), slansy_(char *, 
	    char *, integer *, real *, integer *, real *);
    static real ulp;


#define work_ref(a_1,a_2) work[(a_2)*work_dim1 + a_1]
#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   
       February 29, 1992   


    Purpose   
    =======   

    SSTT22  checks a set of M eigenvalues and eigenvectors,   

        A U = U S   

    where A is symmetric tridiagonal, the columns of U are orthogonal,   
    and S is diagonal (if KBAND=0) or symmetric tridiagonal (if KBAND=1).   
    Two tests are performed:   

       RESULT(1) = | U' A U - S | / ( |A| m ulp )   

       RESULT(2) = | I - U'U | / ( m ulp )   

    Arguments   
    =========   

    N       (input) INTEGER   
            The size of the matrix.  If it is zero, SSTT22 does nothing.   
            It must be at least zero.   

    M       (input) INTEGER   
            The number of eigenpairs to check.  If it is zero, SSTT22   
            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 symmetric tridiagonal.   

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

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

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

    U       (input) REAL 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) REAL array, dimension (LDWORK, M+1)   

    LDWORK  (input) INTEGER   
            The leading dimension of WORK.  LDWORK must be at least   
            max(1,M).   

    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.   

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


       Parameter adjustments */
    --ad;
    --ae;
    --sd;
    --se;
    u_dim1 = *ldu;
    u_offset = 1 + u_dim1 * 1;
    u -= u_offset;
    work_dim1 = *ldwork;
    work_offset = 1 + work_dim1 * 1;
    work -= work_offset;
    --result;

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

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

/*     Do Test 1   

       Compute the 1-norm of A. */

    if (*n > 1) {
	anorm = dabs(ad[1]) + dabs(ae[1]);
	i__1 = *n - 1;
	for (j = 2; j <= i__1; ++j) {
/* Computing MAX */
	    r__4 = anorm, r__5 = (r__1 = ad[j], dabs(r__1)) + (r__2 = ae[j], 
		    dabs(r__2)) + (r__3 = ae[j - 1], dabs(r__3));
	    anorm = dmax(r__4,r__5);
/* L10: */
	}
/* Computing MAX */
	r__3 = anorm, r__4 = (r__1 = ad[*n], dabs(r__1)) + (r__2 = ae[*n - 1],
		 dabs(r__2));
	anorm = dmax(r__3,r__4);
    } else {
	anorm = dabs(ad[1]);
    }
    anorm = dmax(anorm,unfl);

/*     Norm of U'AU - S */

    i__1 = *m;
    for (i__ = 1; i__ <= i__1; ++i__) {
	i__2 = *m;
	for (j = 1; j <= i__2; ++j) {
	    work_ref(i__, j) = 0.f;
	    i__3 = *n;
	    for (k = 1; k <= i__3; ++k) {
		aukj = ad[k] * u_ref(k, j);
		if (k != *n) {
		    aukj += ae[k] * u_ref(k + 1, j);
		}
		if (k != 1) {
		    aukj += ae[k - 1] * u_ref(k - 1, j);
		}
		work_ref(i__, j) = work_ref(i__, j) + u_ref(k, i__) * aukj;
/* L20: */
	    }
/* L30: */
	}
	work_ref(i__, i__) = work_ref(i__, i__) - sd[i__];
	if (*kband == 1) {
	    if (i__ != 1) {
		work_ref(i__, i__ - 1) = work_ref(i__, i__ - 1) - se[i__ - 1];
	    }
	    if (i__ != *n) {
		work_ref(i__, i__ + 1) = work_ref(i__, i__ + 1) - se[i__];
	    }
	}
/* L40: */
    }

    wnorm = slansy_("1", "L", m, &work[work_offset], m, &work_ref(1, *m + 1));

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

/*     Do Test 2   

       Compute  U'U - I */

    sgemm_("T", "N", m, m, n, &c_b12, &u[u_offset], ldu, &u[u_offset], ldu, &
	    c_b13, &work[work_offset], m);

    i__1 = *m;
    for (j = 1; j <= i__1; ++j) {
	work_ref(j, j) = work_ref(j, j) - 1.f;
/* L50: */
    }

/* Computing MIN */
    r__1 = (real) (*m), r__2 = slange_("1", m, m, &work[work_offset], m, &
	    work_ref(1, *m + 1));
    result[2] = dmin(r__1,r__2) / (*m * ulp);

    return 0;

/*     End of SSTT22 */

} /* sstt22_ */

#undef u_ref
#undef work_ref



.