#include "blaswrap.h"
/* ssyt01.f -- translated by f2c (version 20061008).
   You must link the resulting object file with libf2c:
	on Microsoft Windows system, link with libf2c.lib;
	on Linux or Unix systems, link with .../path/to/libf2c.a -lm
	or, if you install libf2c.a in a standard place, with -lf2c -lm
	-- in that order, at the end of the command line, as in
		cc *.o -lf2c -lm
	Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,

		http://www.netlib.org/f2c/libf2c.zip
*/

#include "f2c.h"

/* Table of constant values */

static real c_b5 = 0.f;
static real c_b6 = 1.f;

/* Subroutine */ int ssyt01_(char *uplo, integer *n, real *a, integer *lda, 
	real *afac, integer *ldafac, integer *ipiv, real *c__, integer *ldc, 
	real *rwork, real *resid)
{
    /* System generated locals */
    integer a_dim1, a_offset, afac_dim1, afac_offset, c_dim1, c_offset, i__1, 
	    i__2;

    /* Local variables */
    static integer i__, j;
    static real eps;
    static integer info;
    extern logical lsame_(char *, char *);
    static real anorm;
    extern doublereal slamch_(char *);
    extern /* Subroutine */ int slaset_(char *, integer *, integer *, real *, 
	    real *, real *, integer *);
    extern doublereal slansy_(char *, char *, integer *, real *, integer *, 
	    real *);
    extern /* Subroutine */ int slavsy_(char *, char *, char *, integer *, 
	    integer *, real *, integer *, integer *, real *, integer *, 
	    integer *);


/*  -- LAPACK test routine (version 3.1) --   
       Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..   
       November 2006   


    Purpose   
    =======   

    SSYT01 reconstructs a symmetric indefinite matrix A from its   
    block L*D*L' or U*D*U' factorization and computes the residual   
       norm( C - A ) / ( N * norm(A) * EPS ),   
    where C is the reconstructed matrix and 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 (LDA,N)   
            The original symmetric matrix A.   

    LDA     (input) INTEGER   
            The leading dimension of the array A.  LDA >= max(1,N)   

    AFAC    (input) REAL array, dimension (LDAFAC,N)   
            The factored form of the matrix A.  AFAC contains the block   
            diagonal matrix D and the multipliers used to obtain the   
            factor L or U from the block L*D*L' or U*D*U' factorization   
            as computed by SSYTRF.   

    LDAFAC  (input) INTEGER   
            The leading dimension of the array AFAC.  LDAFAC >= max(1,N).   

    IPIV    (input) INTEGER array, dimension (N)   
            The pivot indices from SSYTRF.   

    C       (workspace) REAL array, dimension (LDC,N)   

    LDC     (integer) INTEGER   
            The leading dimension of the array C.  LDC >= max(1,N).   

    RWORK   (workspace) REAL array, dimension (N)   

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

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


       Quick exit if N = 0.   

       Parameter adjustments */
    a_dim1 = *lda;
    a_offset = 1 + a_dim1;
    a -= a_offset;
    afac_dim1 = *ldafac;
    afac_offset = 1 + afac_dim1;
    afac -= afac_offset;
    --ipiv;
    c_dim1 = *ldc;
    c_offset = 1 + c_dim1;
    c__ -= c_offset;
    --rwork;

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

/*     Determine EPS and the norm of A. */

    eps = slamch_("Epsilon");
    anorm = slansy_("1", uplo, n, &a[a_offset], lda, &rwork[1]);

/*     Initialize C to the identity matrix. */

    slaset_("Full", n, n, &c_b5, &c_b6, &c__[c_offset], ldc);

/*     Call SLAVSY to form the product D * U' (or D * L' ). */

    slavsy_(uplo, "Transpose", "Non-unit", n, n, &afac[afac_offset], ldafac, &
	    ipiv[1], &c__[c_offset], ldc, &info);

/*     Call SLAVSY again to multiply by U (or L ). */

    slavsy_(uplo, "No transpose", "Unit", n, n, &afac[afac_offset], ldafac, &
	    ipiv[1], &c__[c_offset], ldc, &info);

/*     Compute the difference  C - A . */

    if (lsame_(uplo, "U")) {
	i__1 = *n;
	for (j = 1; j <= i__1; ++j) {
	    i__2 = j;
	    for (i__ = 1; i__ <= i__2; ++i__) {
		c__[i__ + j * c_dim1] -= a[i__ + j * a_dim1];
/* L10: */
	    }
/* L20: */
	}
    } else {
	i__1 = *n;
	for (j = 1; j <= i__1; ++j) {
	    i__2 = *n;
	    for (i__ = j; i__ <= i__2; ++i__) {
		c__[i__ + j * c_dim1] -= a[i__ + j * a_dim1];
/* L30: */
	    }
/* L40: */
	}
    }

/*     Compute norm( C - A ) / ( N * norm(A) * EPS ) */

    *resid = slansy_("1", uplo, n, &c__[c_offset], ldc, &rwork[1]);

    if (anorm <= 0.f) {
	if (*resid != 0.f) {
	    *resid = 1.f / eps;
	}
    } else {
	*resid = *resid / (real) (*n) / anorm / eps;
    }

    return 0;

/*     End of SSYT01 */

} /* ssyt01_ */