int
f2c_stbmv(char* uplo, char* trans, char* diag, integer* N, integer* K,
real* A, integer* lda,
real* X, integer* incX)
{
stbmv_(uplo, trans, diag,
N, K, A, lda, X, incX);
return 0;
}
/* Subroutine */ int stbt03_(char *uplo, char *trans, char *diag, integer *n,
integer *kd, integer *nrhs, real *ab, integer *ldab, real *scale,
real *cnorm, real *tscal, real *x, integer *ldx, real *b, integer *
ldb, real *work, real *resid)
{
/* System generated locals */
integer ab_dim1, ab_offset, b_dim1, b_offset, x_dim1, x_offset, i__1;
real r__1, r__2, r__3;
/* Local variables */
static integer j;
extern logical lsame_(char *, char *);
extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *);
static real xscal;
extern /* Subroutine */ int stbmv_(char *, char *, char *, integer *,
integer *, real *, integer *, real *, integer *), scopy_(integer *, real *, integer *, real *, integer *);
static real tnorm, xnorm;
extern /* Subroutine */ int saxpy_(integer *, real *, real *, integer *,
real *, integer *), slabad_(real *, real *);
static integer ix;
extern doublereal slamch_(char *);
static real bignum;
extern integer isamax_(integer *, real *, integer *);
static real smlnum, eps, err;
#define b_ref(a_1,a_2) b[(a_2)*b_dim1 + a_1]
#define x_ref(a_1,a_2) x[(a_2)*x_dim1 + a_1]
#define ab_ref(a_1,a_2) ab[(a_2)*ab_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
=======
STBT03 computes the residual for the solution to a scaled triangular
system of equations A*x = s*b or A'*x = s*b when A is a
triangular band matrix. Here A' is the transpose of A, s is a scalar,
and x and b are N by NRHS matrices. The test ratio is the maximum
over the number of right hand sides of
norm(s*b - op(A)*x) / ( norm(op(A)) * norm(x) * EPS ),
where op(A) denotes A or A' and EPS is the machine epsilon.
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 operation applied to A.
= '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 order of the matrix A. N >= 0.
KD (input) INTEGER
The number of superdiagonals or subdiagonals of the
triangular band matrix A. KD >= 0.
NRHS (input) INTEGER
The number of right hand sides, i.e., the number of columns
of the matrices X and B. 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).
LDAB (input) INTEGER
The leading dimension of the array AB. LDAB >= KD+1.
SCALE (input) REAL
The scaling factor s used in solving the triangular system.
CNORM (input) REAL array, dimension (N)
The 1-norms of the columns of A, not counting the diagonal.
TSCAL (input) REAL
The scaling factor used in computing the 1-norms in CNORM.
CNORM actually contains the column norms of TSCAL*A.
X (input) REAL array, dimension (LDX,NRHS)
The computed solution vectors for the system of linear
equations.
LDX (input) INTEGER
The leading dimension of the array X. LDX >= max(1,N).
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).
WORK (workspace) REAL array, dimension (N)
RESID (output) REAL
The maximum over the number of right hand sides of
norm(op(A)*x - s*b) / ( norm(op(A)) * norm(x) * EPS ).
=====================================================================
Quick exit if N = 0
Parameter adjustments */
ab_dim1 = *ldab;
ab_offset = 1 + ab_dim1 * 1;
ab -= ab_offset;
--cnorm;
x_dim1 = *ldx;
x_offset = 1 + x_dim1 * 1;
x -= x_offset;
b_dim1 = *ldb;
b_offset = 1 + b_dim1 * 1;
b -= b_offset;
--work;
/* Function Body */
if (*n <= 0 || *nrhs <= 0) {
*resid = 0.f;
return 0;
}
eps = slamch_("Epsilon");
smlnum = slamch_("Safe minimum");
bignum = 1.f / smlnum;
slabad_(&smlnum, &bignum);
/* Compute the norm of the triangular matrix A using the column
norms already computed by SLATBS. */
tnorm = 0.f;
if (lsame_(diag, "N")) {
if (lsame_(uplo, "U")) {
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
/* Computing MAX */
r__2 = tnorm, r__3 = *tscal * (r__1 = ab_ref(*kd + 1, j),
dabs(r__1)) + cnorm[j];
tnorm = dmax(r__2,r__3);
/* L10: */
}
} else {
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
/* Computing MAX */
r__2 = tnorm, r__3 = *tscal * (r__1 = ab_ref(1, j), dabs(r__1)
) + cnorm[j];
tnorm = dmax(r__2,r__3);
/* L20: */
}
}
} else {
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
/* Computing MAX */
r__1 = tnorm, r__2 = *tscal + cnorm[j];
tnorm = dmax(r__1,r__2);
/* L30: */
}
}
/* Compute the maximum over the number of right hand sides of
norm(op(A)*x - s*b) / ( norm(op(A)) * norm(x) * EPS ). */
*resid = 0.f;
i__1 = *nrhs;
for (j = 1; j <= i__1; ++j) {
scopy_(n, &x_ref(1, j), &c__1, &work[1], &c__1);
ix = isamax_(n, &work[1], &c__1);
/* Computing MAX */
r__2 = 1.f, r__3 = (r__1 = x_ref(ix, j), dabs(r__1));
xnorm = dmax(r__2,r__3);
xscal = 1.f / xnorm / (real) (*kd + 1);
sscal_(n, &xscal, &work[1], &c__1);
stbmv_(uplo, trans, diag, n, kd, &ab[ab_offset], ldab, &work[1], &
c__1);
r__1 = -(*scale) * xscal;
saxpy_(n, &r__1, &b_ref(1, j), &c__1, &work[1], &c__1);
ix = isamax_(n, &work[1], &c__1);
err = *tscal * (r__1 = work[ix], dabs(r__1));
ix = isamax_(n, &x_ref(1, j), &c__1);
xnorm = (r__1 = x_ref(ix, j), dabs(r__1));
if (err * smlnum <= xnorm) {
if (xnorm > 0.f) {
err /= xnorm;
}
} else {
if (err > 0.f) {
err = 1.f / eps;
}
}
if (err * smlnum <= tnorm) {
if (tnorm > 0.f) {
err /= tnorm;
}
} else {
if (err > 0.f) {
err = 1.f / eps;
}
}
*resid = dmax(*resid,err);
/* L40: */
}
return 0;
/* End of STBT03 */
} /* stbt03_ */
void
stbmv(char uplo, char trans, char diag, int n, int k, float *a, int lda, float *x, int incx )
{
stbmv_( &uplo, &trans, &diag, &n, &k, a, &lda, x, &incx );
}
/* Subroutine */ int stbt02_(char *uplo, char *trans, char *diag, integer *n,
integer *kd, integer *nrhs, real *ab, integer *ldab, real *x, integer
*ldx, real *b, integer *ldb, real *work, real *resid)
{
/* System generated locals */
integer ab_dim1, ab_offset, b_dim1, b_offset, x_dim1, x_offset, i__1;
real r__1, r__2;
/* Local variables */
integer j;
real eps;
extern logical lsame_(char *, char *);
real anorm, bnorm;
extern doublereal sasum_(integer *, real *, integer *);
extern /* Subroutine */ int stbmv_(char *, char *, char *, integer *,
integer *, real *, integer *, real *, integer *), scopy_(integer *, real *, integer *, real *, integer *);
real xnorm;
extern /* Subroutine */ int saxpy_(integer *, real *, real *, integer *,
real *, integer *);
extern doublereal slamch_(char *), slantb_(char *, char *, char *,
integer *, integer *, real *, integer *, real *);
/* -- LAPACK test routine (version 3.1) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* STBT02 computes the residual for the computed solution to a */
/* triangular system of linear equations A*x = b or A' *x = b when */
/* A is a triangular band matrix. Here A' is the transpose of A and */
/* x and b are N by NRHS matrices. The test ratio is the maximum over */
/* the number of right hand sides of */
/* norm(b - op(A)*x) / ( norm(op(A)) * norm(x) * EPS ), */
/* where op(A) denotes A or A' and EPS is the machine epsilon. */
/* 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 operation applied to A. */
/* = '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 order of the matrix A. N >= 0. */
/* KD (input) INTEGER */
/* The number of superdiagonals or subdiagonals of the */
/* triangular band matrix A. KD >= 0. */
/* NRHS (input) INTEGER */
/* The number of right hand sides, i.e., the number of columns */
/* of the matrices X and B. 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). */
/* LDAB (input) INTEGER */
/* The leading dimension of the array AB. LDAB >= KD+1. */
/* X (input) REAL array, dimension (LDX,NRHS) */
/* The computed solution vectors for the system of linear */
/* equations. */
/* LDX (input) INTEGER */
/* The leading dimension of the array X. LDX >= max(1,N). */
/* 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). */
/* WORK (workspace) REAL array, dimension (N) */
/* RESID (output) REAL */
/* The maximum over the number of right hand sides of */
/* norm(op(A)*x - b) / ( norm(op(A)) * norm(x) * EPS ). */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Quick exit if N = 0 or NRHS = 0 */
/* Parameter adjustments */
ab_dim1 = *ldab;
ab_offset = 1 + ab_dim1;
ab -= ab_offset;
x_dim1 = *ldx;
x_offset = 1 + x_dim1;
x -= x_offset;
b_dim1 = *ldb;
b_offset = 1 + b_dim1;
b -= b_offset;
--work;
/* Function Body */
if (*n <= 0 || *nrhs <= 0) {
*resid = 0.f;
return 0;
}
/* Compute the 1-norm of A or A'. */
if (lsame_(trans, "N")) {
anorm = slantb_("1", uplo, diag, n, kd, &ab[ab_offset], ldab, &work[1]
);
} else {
anorm = slantb_("I", uplo, diag, n, kd, &ab[ab_offset], ldab, &work[1]
);
}
/* Exit with RESID = 1/EPS if ANORM = 0. */
eps = slamch_("Epsilon");
if (anorm <= 0.f) {
*resid = 1.f / eps;
return 0;
}
/* Compute the maximum over the number of right hand sides of */
/* norm(op(A)*x - b) / ( norm(op(A)) * norm(x) * EPS ). */
*resid = 0.f;
i__1 = *nrhs;
for (j = 1; j <= i__1; ++j) {
scopy_(n, &x[j * x_dim1 + 1], &c__1, &work[1], &c__1);
stbmv_(uplo, trans, diag, n, kd, &ab[ab_offset], ldab, &work[1], &
c__1);
saxpy_(n, &c_b10, &b[j * b_dim1 + 1], &c__1, &work[1], &c__1);
bnorm = sasum_(n, &work[1], &c__1);
xnorm = sasum_(n, &x[j * x_dim1 + 1], &c__1);
if (xnorm <= 0.f) {
*resid = 1.f / eps;
} else {
/* Computing MAX */
r__1 = *resid, r__2 = bnorm / anorm / xnorm / eps;
*resid = dmax(r__1,r__2);
}
/* L10: */
}
return 0;
/* End of STBT02 */
} /* stbt02_ */
