#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 integer c__1 = 1;
static real c_b14 = 1.f;

/* Subroutine */ int sppt01_(char *uplo, integer *n, real *a, real *afac, 
	real *rwork, real *resid)
{
    /* System generated locals */
    integer i__1;

    /* Local variables */
    extern doublereal sdot_(integer *, real *, integer *, real *, integer *);
    extern /* Subroutine */ int sspr_(char *, integer *, real *, real *, 
	    integer *, real *);
    static integer i__, k;
    static real t;
    extern logical lsame_(char *, char *);
    extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *);
    static real anorm;
    extern /* Subroutine */ int stpmv_(char *, char *, char *, integer *, 
	    real *, real *, integer *);
    static integer kc;
    extern doublereal slamch_(char *), slansp_(char *, char *, 
	    integer *, real *, real *);
    static real eps;
    static integer npp;


/*  -- 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   
    =======   

    SPPT01 reconstructs a symmetric positive definite packed matrix A   
    from its L*L' or U'*U factorization and computes the residual   
       norm( L*L' - A ) / ( N * norm(A) * EPS ) or   
       norm( U'*U - A ) / ( N * norm(A) * EPS ),   
    where EPS is the machine epsilon.   

    Arguments   
    ==========   

    UPLO    (input) CHARACTER*1   
            Specifies whether the upper or lower triangular part of the   
            symmetric matrix A is stored:   
            = 'U':  Upper triangular   
            = 'L':  Lower triangular   

    N       (input) INTEGER   
            The number of rows and columns of the matrix A.  N >= 0.   

    A       (input) REAL array, dimension (N*(N+1)/2)   
            The original symmetric matrix A, stored as a packed   
            triangular matrix.   

    AFAC    (input/output) REAL array, dimension (N*(N+1)/2)   
            On entry, the factor L or U from the L*L' or U'*U   
            factorization of A, stored as a packed triangular matrix.   
            Overwritten with the reconstructed matrix, and then with the   
            difference L*L' - A (or U'*U - A).   

    RWORK   (workspace) REAL array, dimension (N)   

    RESID   (output) REAL   
            If UPLO = 'L', norm(L*L' - A) / ( N * norm(A) * EPS )   
            If UPLO = 'U', norm(U'*U - A) / ( N * norm(A) * EPS )   

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


       Quick exit if N = 0   

       Parameter adjustments */
    --rwork;
    --afac;
    --a;

    /* Function Body */
    if (*n <= 0) {
	*resid = 0.f;
	return 0;
    }

/*     Exit with RESID = 1/EPS if ANORM = 0. */

    eps = slamch_("Epsilon");
    anorm = slansp_("1", uplo, n, &a[1], &rwork[1]);
    if (anorm <= 0.f) {
	*resid = 1.f / eps;
	return 0;
    }

/*     Compute the product U'*U, overwriting U. */

    if (lsame_(uplo, "U")) {
	kc = *n * (*n - 1) / 2 + 1;
	for (k = *n; k >= 1; --k) {

/*           Compute the (K,K) element of the result. */

	    t = sdot_(&k, &afac[kc], &c__1, &afac[kc], &c__1);
	    afac[kc + k - 1] = t;

/*           Compute the rest of column K. */

	    if (k > 1) {
		i__1 = k - 1;
		stpmv_("Upper", "Transpose", "Non-unit", &i__1, &afac[1], &
			afac[kc], &c__1);
		kc -= k - 1;
	    }
/* L10: */
	}

/*     Compute the product L*L', overwriting L. */

    } else {
	kc = *n * (*n + 1) / 2;
	for (k = *n; k >= 1; --k) {

/*           Add a multiple of column K of the factor L to each of   
             columns K+1 through N. */

	    if (k < *n) {
		i__1 = *n - k;
		sspr_("Lower", &i__1, &c_b14, &afac[kc + 1], &c__1, &afac[kc 
			+ *n - k + 1]);
	    }

/*           Scale column K by the diagonal element. */

	    t = afac[kc];
	    i__1 = *n - k + 1;
	    sscal_(&i__1, &t, &afac[kc], &c__1);

	    kc -= *n - k + 2;
/* L20: */
	}
    }

/*     Compute the difference  L*L' - A (or U'*U - A). */

    npp = *n * (*n + 1) / 2;
    i__1 = npp;
    for (i__ = 1; i__ <= i__1; ++i__) {
	afac[i__] -= a[i__];
/* L30: */
    }

/*     Compute norm( L*U - A ) / ( N * norm(A) * EPS ) */

    *resid = slansp_("1", uplo, n, &afac[1], &rwork[1]);

    *resid = *resid / (real) (*n) / anorm / eps;

    return 0;

/*     End of SPPT01 */

} /* sppt01_ */

