/* chetrs.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"
#include "blaswrap.h"
/* Table of constant values */
static complex c_b1 = {1.f,0.f};
static integer c__1 = 1;
/* Subroutine */ int chetrs_(char *uplo, integer *n, integer *nrhs, complex *
a, integer *lda, integer *ipiv, complex *b, integer *ldb, integer *
info)
{
/* System generated locals */
integer a_dim1, a_offset, b_dim1, b_offset, i__1, i__2;
complex q__1, q__2, q__3;
/* Builtin functions */
void c_div(complex *, complex *, complex *), r_cnjg(complex *, complex *);
/* Local variables */
integer j, k;
real s;
complex ak, bk;
integer kp;
complex akm1, bkm1, akm1k;
extern logical lsame_(char *, char *);
complex denom;
extern /* Subroutine */ int cgemv_(char *, integer *, integer *, complex *
, complex *, integer *, complex *, integer *, complex *, complex *
, integer *), cgeru_(integer *, integer *, complex *,
complex *, integer *, complex *, integer *, complex *, integer *),
cswap_(integer *, complex *, integer *, complex *, integer *);
logical upper;
extern /* Subroutine */ int clacgv_(integer *, complex *, integer *),
csscal_(integer *, real *, complex *, integer *), xerbla_(char *,
integer *);
/* -- LAPACK routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* CHETRS solves a system of linear equations A*X = B with a complex */
/* Hermitian matrix A using the factorization A = U*D*U**H or */
/* A = L*D*L**H computed by CHETRF. */
/* Arguments */
/* ========= */
/* UPLO (input) CHARACTER*1 */
/* Specifies whether the details of the factorization are stored */
/* as an upper or lower triangular matrix. */
/* = 'U': Upper triangular, form is A = U*D*U**H; */
/* = 'L': Lower triangular, form is A = L*D*L**H. */
/* N (input) INTEGER */
/* The order of the matrix A. N >= 0. */
/* NRHS (input) INTEGER */
/* The number of right hand sides, i.e., the number of columns */
/* of the matrix B. NRHS >= 0. */
/* A (input) COMPLEX array, dimension (LDA,N) */
/* The block diagonal matrix D and the multipliers used to */
/* obtain the factor U or L as computed by CHETRF. */
/* LDA (input) INTEGER */
/* The leading dimension of the array A. LDA >= max(1,N). */
/* IPIV (input) INTEGER array, dimension (N) */
/* Details of the interchanges and the block structure of D */
/* as determined by CHETRF. */
/* B (input/output) COMPLEX array, dimension (LDB,NRHS) */
/* On entry, the right hand side matrix B. */
/* On exit, the solution matrix X. */
/* LDB (input) INTEGER */
/* The leading dimension of the array B. LDB >= max(1,N). */
/* INFO (output) INTEGER */
/* = 0: successful exit */
/* < 0: if INFO = -i, the i-th argument had an illegal value */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Parameter adjustments */
a_dim1 = *lda;
a_offset = 1 + a_dim1;
a -= a_offset;
--ipiv;
b_dim1 = *ldb;
b_offset = 1 + b_dim1;
b -= b_offset;
/* Function Body */
*info = 0;
upper = lsame_(uplo, "U");
if (! upper && ! lsame_(uplo, "L")) {
*info = -1;
} else if (*n < 0) {
*info = -2;
} else if (*nrhs < 0) {
*info = -3;
} else if (*lda < max(1,*n)) {
*info = -5;
} else if (*ldb < max(1,*n)) {
*info = -8;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("CHETRS", &i__1);
return 0;
}
/* Quick return if possible */
if (*n == 0 || *nrhs == 0) {
return 0;
}
if (upper) {
/* Solve A*X = B, where A = U*D*U'. */
/* First solve U*D*X = B, overwriting B with X. */
/* K is the main loop index, decreasing from N to 1 in steps of */
/* 1 or 2, depending on the size of the diagonal blocks. */
k = *n;
L10:
/* If K < 1, exit from loop. */
if (k < 1) {
goto L30;
}
if (ipiv[k] > 0) {
/* 1 x 1 diagonal block */
/* Interchange rows K and IPIV(K). */
kp = ipiv[k];
if (kp != k) {
cswap_(nrhs, &b[k + b_dim1], ldb, &b[kp + b_dim1], ldb);
}
/* Multiply by inv(U(K)), where U(K) is the transformation */
/* stored in column K of A. */
i__1 = k - 1;
q__1.r = -1.f, q__1.i = -0.f;
cgeru_(&i__1, nrhs, &q__1, &a[k * a_dim1 + 1], &c__1, &b[k +
b_dim1], ldb, &b[b_dim1 + 1], ldb);
/* Multiply by the inverse of the diagonal block. */
i__1 = k + k * a_dim1;
s = 1.f / a[i__1].r;
csscal_(nrhs, &s, &b[k + b_dim1], ldb);
--k;
} else {
/* 2 x 2 diagonal block */
/* Interchange rows K-1 and -IPIV(K). */
kp = -ipiv[k];
if (kp != k - 1) {
cswap_(nrhs, &b[k - 1 + b_dim1], ldb, &b[kp + b_dim1], ldb);
}
/* Multiply by inv(U(K)), where U(K) is the transformation */
/* stored in columns K-1 and K of A. */
i__1 = k - 2;
q__1.r = -1.f, q__1.i = -0.f;
cgeru_(&i__1, nrhs, &q__1, &a[k * a_dim1 + 1], &c__1, &b[k +
b_dim1], ldb, &b[b_dim1 + 1], ldb);
i__1 = k - 2;
q__1.r = -1.f, q__1.i = -0.f;
cgeru_(&i__1, nrhs, &q__1, &a[(k - 1) * a_dim1 + 1], &c__1, &b[k
- 1 + b_dim1], ldb, &b[b_dim1 + 1], ldb);
/* Multiply by the inverse of the diagonal block. */
i__1 = k - 1 + k * a_dim1;
akm1k.r = a[i__1].r, akm1k.i = a[i__1].i;
c_div(&q__1, &a[k - 1 + (k - 1) * a_dim1], &akm1k);
akm1.r = q__1.r, akm1.i = q__1.i;
r_cnjg(&q__2, &akm1k);
c_div(&q__1, &a[k + k * a_dim1], &q__2);
ak.r = q__1.r, ak.i = q__1.i;
q__2.r = akm1.r * ak.r - akm1.i * ak.i, q__2.i = akm1.r * ak.i +
akm1.i * ak.r;
q__1.r = q__2.r - 1.f, q__1.i = q__2.i - 0.f;
denom.r = q__1.r, denom.i = q__1.i;
i__1 = *nrhs;
for (j = 1; j <= i__1; ++j) {
c_div(&q__1, &b[k - 1 + j * b_dim1], &akm1k);
bkm1.r = q__1.r, bkm1.i = q__1.i;
r_cnjg(&q__2, &akm1k);
c_div(&q__1, &b[k + j * b_dim1], &q__2);
bk.r = q__1.r, bk.i = q__1.i;
i__2 = k - 1 + j * b_dim1;
q__3.r = ak.r * bkm1.r - ak.i * bkm1.i, q__3.i = ak.r *
bkm1.i + ak.i * bkm1.r;
q__2.r = q__3.r - bk.r, q__2.i = q__3.i - bk.i;
c_div(&q__1, &q__2, &denom);
b[i__2].r = q__1.r, b[i__2].i = q__1.i;
i__2 = k + j * b_dim1;
q__3.r = akm1.r * bk.r - akm1.i * bk.i, q__3.i = akm1.r *
bk.i + akm1.i * bk.r;
q__2.r = q__3.r - bkm1.r, q__2.i = q__3.i - bkm1.i;
c_div(&q__1, &q__2, &denom);
b[i__2].r = q__1.r, b[i__2].i = q__1.i;
/* L20: */
}
k += -2;
}
goto L10;
L30:
/* Next solve U'*X = B, overwriting B with X. */
/* K is the main loop index, increasing from 1 to N in steps of */
/* 1 or 2, depending on the size of the diagonal blocks. */
k = 1;
L40:
/* If K > N, exit from loop. */
if (k > *n) {
goto L50;
}
if (ipiv[k] > 0) {
/* 1 x 1 diagonal block */
/* Multiply by inv(U'(K)), where U(K) is the transformation */
/* stored in column K of A. */
if (k > 1) {
clacgv_(nrhs, &b[k + b_dim1], ldb);
i__1 = k - 1;
q__1.r = -1.f, q__1.i = -0.f;
cgemv_("Conjugate transpose", &i__1, nrhs, &q__1, &b[b_offset]
, ldb, &a[k * a_dim1 + 1], &c__1, &c_b1, &b[k +
b_dim1], ldb);
clacgv_(nrhs, &b[k + b_dim1], ldb);
}
/* Interchange rows K and IPIV(K). */
kp = ipiv[k];
if (kp != k) {
cswap_(nrhs, &b[k + b_dim1], ldb, &b[kp + b_dim1], ldb);
}
++k;
} else {
/* 2 x 2 diagonal block */
/* Multiply by inv(U'(K+1)), where U(K+1) is the transformation */
/* stored in columns K and K+1 of A. */
if (k > 1) {
clacgv_(nrhs, &b[k + b_dim1], ldb);
i__1 = k - 1;
q__1.r = -1.f, q__1.i = -0.f;
cgemv_("Conjugate transpose", &i__1, nrhs, &q__1, &b[b_offset]
, ldb, &a[k * a_dim1 + 1], &c__1, &c_b1, &b[k +
b_dim1], ldb);
clacgv_(nrhs, &b[k + b_dim1], ldb);
clacgv_(nrhs, &b[k + 1 + b_dim1], ldb);
i__1 = k - 1;
q__1.r = -1.f, q__1.i = -0.f;
cgemv_("Conjugate transpose", &i__1, nrhs, &q__1, &b[b_offset]
, ldb, &a[(k + 1) * a_dim1 + 1], &c__1, &c_b1, &b[k +
1 + b_dim1], ldb);
clacgv_(nrhs, &b[k + 1 + b_dim1], ldb);
}
/* Interchange rows K and -IPIV(K). */
kp = -ipiv[k];
if (kp != k) {
cswap_(nrhs, &b[k + b_dim1], ldb, &b[kp + b_dim1], ldb);
}
k += 2;
}
goto L40;
L50:
;
} else {
/* Solve A*X = B, where A = L*D*L'. */
/* First solve L*D*X = B, overwriting B with X. */
/* K is the main loop index, increasing from 1 to N in steps of */
/* 1 or 2, depending on the size of the diagonal blocks. */
k = 1;
L60:
/* If K > N, exit from loop. */
if (k > *n) {
goto L80;
}
if (ipiv[k] > 0) {
/* 1 x 1 diagonal block */
/* Interchange rows K and IPIV(K). */
kp = ipiv[k];
if (kp != k) {
cswap_(nrhs, &b[k + b_dim1], ldb, &b[kp + b_dim1], ldb);
}
/* Multiply by inv(L(K)), where L(K) is the transformation */
/* stored in column K of A. */
if (k < *n) {
i__1 = *n - k;
q__1.r = -1.f, q__1.i = -0.f;
cgeru_(&i__1, nrhs, &q__1, &a[k + 1 + k * a_dim1], &c__1, &b[
k + b_dim1], ldb, &b[k + 1 + b_dim1], ldb);
}
/* Multiply by the inverse of the diagonal block. */
i__1 = k + k * a_dim1;
s = 1.f / a[i__1].r;
csscal_(nrhs, &s, &b[k + b_dim1], ldb);
++k;
} else {
/* 2 x 2 diagonal block */
/* Interchange rows K+1 and -IPIV(K). */
kp = -ipiv[k];
if (kp != k + 1) {
cswap_(nrhs, &b[k + 1 + b_dim1], ldb, &b[kp + b_dim1], ldb);
}
/* Multiply by inv(L(K)), where L(K) is the transformation */
/* stored in columns K and K+1 of A. */
if (k < *n - 1) {
i__1 = *n - k - 1;
q__1.r = -1.f, q__1.i = -0.f;
cgeru_(&i__1, nrhs, &q__1, &a[k + 2 + k * a_dim1], &c__1, &b[
k + b_dim1], ldb, &b[k + 2 + b_dim1], ldb);
i__1 = *n - k - 1;
q__1.r = -1.f, q__1.i = -0.f;
cgeru_(&i__1, nrhs, &q__1, &a[k + 2 + (k + 1) * a_dim1], &
c__1, &b[k + 1 + b_dim1], ldb, &b[k + 2 + b_dim1],
ldb);
}
/* Multiply by the inverse of the diagonal block. */
i__1 = k + 1 + k * a_dim1;
akm1k.r = a[i__1].r, akm1k.i = a[i__1].i;
r_cnjg(&q__2, &akm1k);
c_div(&q__1, &a[k + k * a_dim1], &q__2);
akm1.r = q__1.r, akm1.i = q__1.i;
c_div(&q__1, &a[k + 1 + (k + 1) * a_dim1], &akm1k);
ak.r = q__1.r, ak.i = q__1.i;
q__2.r = akm1.r * ak.r - akm1.i * ak.i, q__2.i = akm1.r * ak.i +
akm1.i * ak.r;
q__1.r = q__2.r - 1.f, q__1.i = q__2.i - 0.f;
denom.r = q__1.r, denom.i = q__1.i;
i__1 = *nrhs;
for (j = 1; j <= i__1; ++j) {
r_cnjg(&q__2, &akm1k);
c_div(&q__1, &b[k + j * b_dim1], &q__2);
bkm1.r = q__1.r, bkm1.i = q__1.i;
c_div(&q__1, &b[k + 1 + j * b_dim1], &akm1k);
bk.r = q__1.r, bk.i = q__1.i;
i__2 = k + j * b_dim1;
q__3.r = ak.r * bkm1.r - ak.i * bkm1.i, q__3.i = ak.r *
bkm1.i + ak.i * bkm1.r;
q__2.r = q__3.r - bk.r, q__2.i = q__3.i - bk.i;
c_div(&q__1, &q__2, &denom);
b[i__2].r = q__1.r, b[i__2].i = q__1.i;
i__2 = k + 1 + j * b_dim1;
q__3.r = akm1.r * bk.r - akm1.i * bk.i, q__3.i = akm1.r *
bk.i + akm1.i * bk.r;
q__2.r = q__3.r - bkm1.r, q__2.i = q__3.i - bkm1.i;
c_div(&q__1, &q__2, &denom);
b[i__2].r = q__1.r, b[i__2].i = q__1.i;
/* L70: */
}
k += 2;
}
goto L60;
L80:
/* Next solve L'*X = B, overwriting B with X. */
/* K is the main loop index, decreasing from N to 1 in steps of */
/* 1 or 2, depending on the size of the diagonal blocks. */
k = *n;
L90:
/* If K < 1, exit from loop. */
if (k < 1) {
goto L100;
}
if (ipiv[k] > 0) {
/* 1 x 1 diagonal block */
/* Multiply by inv(L'(K)), where L(K) is the transformation */
/* stored in column K of A. */
if (k < *n) {
clacgv_(nrhs, &b[k + b_dim1], ldb);
i__1 = *n - k;
q__1.r = -1.f, q__1.i = -0.f;
cgemv_("Conjugate transpose", &i__1, nrhs, &q__1, &b[k + 1 +
b_dim1], ldb, &a[k + 1 + k * a_dim1], &c__1, &c_b1, &
b[k + b_dim1], ldb);
clacgv_(nrhs, &b[k + b_dim1], ldb);
}
/* Interchange rows K and IPIV(K). */
kp = ipiv[k];
if (kp != k) {
cswap_(nrhs, &b[k + b_dim1], ldb, &b[kp + b_dim1], ldb);
}
--k;
} else {
/* 2 x 2 diagonal block */
/* Multiply by inv(L'(K-1)), where L(K-1) is the transformation */
/* stored in columns K-1 and K of A. */
if (k < *n) {
clacgv_(nrhs, &b[k + b_dim1], ldb);
i__1 = *n - k;
q__1.r = -1.f, q__1.i = -0.f;
cgemv_("Conjugate transpose", &i__1, nrhs, &q__1, &b[k + 1 +
b_dim1], ldb, &a[k + 1 + k * a_dim1], &c__1, &c_b1, &
b[k + b_dim1], ldb);
clacgv_(nrhs, &b[k + b_dim1], ldb);
clacgv_(nrhs, &b[k - 1 + b_dim1], ldb);
i__1 = *n - k;
q__1.r = -1.f, q__1.i = -0.f;
cgemv_("Conjugate transpose", &i__1, nrhs, &q__1, &b[k + 1 +
b_dim1], ldb, &a[k + 1 + (k - 1) * a_dim1], &c__1, &
c_b1, &b[k - 1 + b_dim1], ldb);
clacgv_(nrhs, &b[k - 1 + b_dim1], ldb);
}
/* Interchange rows K and -IPIV(K). */
kp = -ipiv[k];
if (kp != k) {
cswap_(nrhs, &b[k + b_dim1], ldb, &b[kp + b_dim1], ldb);
}
k += -2;
}
goto L90;
L100:
;
}
return 0;
/* End of CHETRS */
} /* chetrs_ */