#include "blaswrap.h"
/* stbt05.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 integer c__1 = 1;  /* Subroutine */ int stbt05_(char *uplo, char *trans, char *diag, integer *n,  	integer *kd, integer *nrhs, real *ab, integer *ldab, real *b, integer  	*ldb, real *x, integer *ldx, real *xact, integer *ldxact, real *ferr,  	real *berr, real *reslts  	)
{
    /* System generated locals */
    integer ab_dim1, ab_offset, b_dim1, b_offset, x_dim1, x_offset, xact_dim1,
	     xact_offset, i__1, i__2, i__3, i__4;
    real r__1, r__2, r__3;

    /* Local variables */
    static integer i__, j, k, nz, ifu;
    static real eps, tmp, diff, axbi;
    static integer imax;
    static real unfl, ovfl;
    static logical unit;
    extern logical lsame_(char *, char *);
    static logical upper;
    static real xnorm;
    extern doublereal slamch_(char *);
    static real errbnd;
    extern integer isamax_(integer *, real *, integer *);
    static logical notran;


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


    Purpose   
    =======   

    STBT05 tests the error bounds from iterative refinement for the   
    computed solution to a system of equations A*X = B, where A is a   
    triangular band matrix.   

    RESLTS(1) = test of the error bound   
              = norm(X - XACT) / ( norm(X) * FERR )   

    A large value is returned if this ratio is not less than one.   

    RESLTS(2) = residual from the iterative refinement routine   
              = the maximum of BERR / ( NZ*EPS + (*) ), where   
                (*) = NZ*UNFL / (min_i (abs(A)*abs(X) +abs(b))_i )   
                and NZ = max. number of nonzeros in any row of A, plus 1   

    Arguments   
    =========   

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

    TRANS   (input) CHARACTER*1   
            Specifies the form of the system of equations.   
            = 'N':  A * X = B  (No transpose)   
            = 'T':  A'* X = B  (Transpose)   
            = 'C':  A'* X = B  (Conjugate transpose = Transpose)   

    DIAG    (input) CHARACTER*1   
            Specifies whether or not the matrix A is unit triangular.   
            = 'N':  Non-unit triangular   
            = 'U':  Unit triangular   

    N       (input) INTEGER   
            The number of rows of the matrices X, B, and XACT, and the   
            order of the matrix A.  N >= 0.   

    KD      (input) INTEGER   
            The number of super-diagonals of the matrix A if UPLO = 'U',   
            or the number of sub-diagonals if UPLO = 'L'.  KD >= 0.   

    NRHS    (input) INTEGER   
            The number of columns of the matrices X, B, and XACT.   
            NRHS >= 0.   

    AB      (input) REAL array, dimension (LDAB,N)   
            The upper or lower triangular band matrix A, stored in the   
            first kd+1 rows of the array. The j-th column of A is stored   
            in the j-th column of the array AB as follows:   
            if UPLO = 'U', AB(kd+1+i-j,j) = A(i,j) for max(1,j-kd)<=i<=j;   
            if UPLO = 'L', AB(1+i-j,j)    = A(i,j) for j<=i<=min(n,j+kd).   
            If DIAG = 'U', the diagonal elements of A are not referenced   
            and are assumed to be 1.   

    LDAB    (input) INTEGER   
            The leading dimension of the array AB.  LDAB >= KD+1.   

    B       (input) REAL array, dimension (LDB,NRHS)   
            The right hand side vectors for the system of linear   
            equations.   

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

    X       (input) REAL array, dimension (LDX,NRHS)   
            The computed solution vectors.  Each vector is stored as a   
            column of the matrix X.   

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

    XACT    (input) REAL array, dimension (LDX,NRHS)   
            The exact solution vectors.  Each vector is stored as a   
            column of the matrix XACT.   

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

    FERR    (input) REAL array, dimension (NRHS)   
            The estimated forward error bounds for each solution vector   
            X.  If XTRUE is the true solution, FERR bounds the magnitude   
            of the largest entry in (X - XTRUE) divided by the magnitude   
            of the largest entry in X.   

    BERR    (input) REAL array, dimension (NRHS)   
            The componentwise relative backward error of each solution   
            vector (i.e., the smallest relative change in any entry of A   
            or B that makes X an exact solution).   

    RESLTS  (output) REAL array, dimension (2)   
            The maximum over the NRHS solution vectors of the ratios:   
            RESLTS(1) = norm(X - XACT) / ( norm(X) * FERR )   
            RESLTS(2) = BERR / ( NZ*EPS + (*) )   

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


       Quick exit if N = 0 or NRHS = 0.   

       Parameter adjustments */
    ab_dim1 = *ldab;
    ab_offset = 1 + ab_dim1;
    ab -= ab_offset;
    b_dim1 = *ldb;
    b_offset = 1 + b_dim1;
    b -= b_offset;
    x_dim1 = *ldx;
    x_offset = 1 + x_dim1;
    x -= x_offset;
    xact_dim1 = *ldxact;
    xact_offset = 1 + xact_dim1;
    xact -= xact_offset;
    --ferr;
    --berr;
    --reslts;

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

    eps = slamch_("Epsilon");
    unfl = slamch_("Safe minimum");
    ovfl = 1.f / unfl;
    upper = lsame_(uplo, "U");
    notran = lsame_(trans, "N");
    unit = lsame_(diag, "U");
/* Computing MIN */
    i__1 = *kd, i__2 = *n - 1;
    nz = min(i__1,i__2) + 1;

/*     Test 1:  Compute the maximum of   
          norm(X - XACT) / ( norm(X) * FERR )   
       over all the vectors X and XACT using the infinity-norm. */

    errbnd = 0.f;
    i__1 = *nrhs;
    for (j = 1; j <= i__1; ++j) {
	imax = isamax_(n, &x[j * x_dim1 + 1], &c__1);
/* Computing MAX */
	r__2 = (r__1 = x[imax + j * x_dim1], dabs(r__1));
	xnorm = dmax(r__2,unfl);
	diff = 0.f;
	i__2 = *n;
	for (i__ = 1; i__ <= i__2; ++i__) {
/* Computing MAX */
	    r__2 = diff, r__3 = (r__1 = x[i__ + j * x_dim1] - xact[i__ + j * 
		    xact_dim1], dabs(r__1));
	    diff = dmax(r__2,r__3);
/* L10: */
	}

	if (xnorm > 1.f) {
	    goto L20;
	} else if (diff <= ovfl * xnorm) {
	    goto L20;
	} else {
	    errbnd = 1.f / eps;
	    goto L30;
	}

L20:
	if (diff / xnorm <= ferr[j]) {
/* Computing MAX */
	    r__1 = errbnd, r__2 = diff / xnorm / ferr[j];
	    errbnd = dmax(r__1,r__2);
	} else {
	    errbnd = 1.f / eps;
	}
L30:
	;
    }
    reslts[1] = errbnd;

/*     Test 2:  Compute the maximum of BERR / ( NZ*EPS + (*) ), where   
       (*) = NZ*UNFL / (min_i (abs(A)*abs(X) +abs(b))_i ) */

    ifu = 0;
    if (unit) {
	ifu = 1;
    }
    i__1 = *nrhs;
    for (k = 1; k <= i__1; ++k) {
	i__2 = *n;
	for (i__ = 1; i__ <= i__2; ++i__) {
	    tmp = (r__1 = b[i__ + k * b_dim1], dabs(r__1));
	    if (upper) {
		if (! notran) {
/* Computing MAX */
		    i__3 = i__ - *kd;
		    i__4 = i__ - ifu;
		    for (j = max(i__3,1); j <= i__4; ++j) {
			tmp += (r__1 = ab[*kd + 1 - i__ + j + i__ * ab_dim1], 
				dabs(r__1)) * (r__2 = x[j + k * x_dim1], dabs(
				r__2));
/* L40: */
		    }
		    if (unit) {
			tmp += (r__1 = x[i__ + k * x_dim1], dabs(r__1));
		    }
		} else {
		    if (unit) {
			tmp += (r__1 = x[i__ + k * x_dim1], dabs(r__1));
		    }
/* Computing MIN */
		    i__3 = i__ + *kd;
		    i__4 = min(i__3,*n);
		    for (j = i__ + ifu; j <= i__4; ++j) {
			tmp += (r__1 = ab[*kd + 1 + i__ - j + j * ab_dim1], 
				dabs(r__1)) * (r__2 = x[j + k * x_dim1], dabs(
				r__2));
/* L50: */
		    }
		}
	    } else {
		if (notran) {
/* Computing MAX */
		    i__4 = i__ - *kd;
		    i__3 = i__ - ifu;
		    for (j = max(i__4,1); j <= i__3; ++j) {
			tmp += (r__1 = ab[i__ + 1 - j + j * ab_dim1], dabs(
				r__1)) * (r__2 = x[j + k * x_dim1], dabs(r__2) );
/* L60: */
		    }
		    if (unit) {
			tmp += (r__1 = x[i__ + k * x_dim1], dabs(r__1));
		    }
		} else {
		    if (unit) {
			tmp += (r__1 = x[i__ + k * x_dim1], dabs(r__1));
		    }
/* Computing MIN */
		    i__4 = i__ + *kd;
		    i__3 = min(i__4,*n);
		    for (j = i__ + ifu; j <= i__3; ++j) {
			tmp += (r__1 = ab[j + 1 - i__ + i__ * ab_dim1], dabs(
				r__1)) * (r__2 = x[j + k * x_dim1], dabs(r__2) );
/* L70: */
		    }
		}
	    }
	    if (i__ == 1) {
		axbi = tmp;
	    } else {
		axbi = dmin(axbi,tmp);
	    }
/* L80: */
	}
/* Computing MAX */
	r__1 = axbi, r__2 = nz * unfl;
	tmp = berr[k] / (nz * eps + nz * unfl / dmax(r__1,r__2));
	if (k == 1) {
	    reslts[2] = tmp;
	} else {
	    reslts[2] = dmax(reslts[2],tmp);
	}
/* L90: */
    }

    return 0;

/*     End of STBT05 */

} /* stbt05_ */