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/* cgttrs.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 integer c__1 = 1;
static integer c_n1 = -1;
/* Subroutine */ int cgttrs_(char *trans, integer *n, integer *nrhs, complex *
dl, complex *d__, complex *du, complex *du2, integer *ipiv, complex *
b, integer *ldb, integer *info)
{
/* System generated locals */
integer b_dim1, b_offset, i__1, i__2, i__3;
/* Local variables */
integer j, jb, nb;
extern /* Subroutine */ int cgtts2_(integer *, integer *, integer *,
complex *, complex *, complex *, complex *, integer *, complex *,
integer *), xerbla_(char *, integer *);
extern integer ilaenv_(integer *, char *, char *, integer *, integer *,
integer *, integer *);
integer itrans;
logical notran;
/* -- LAPACK routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* CGTTRS solves one of the systems of equations */
/* A * X = B, A**T * X = B, or A**H * X = B, */
/* with a tridiagonal matrix A using the LU factorization computed */
/* by CGTTRF. */
/* Arguments */
/* ========= */
/* TRANS (input) CHARACTER*1 */
/* Specifies the form of the system of equations. */
/* = 'N': A * X = B (No transpose) */
/* = 'T': A**T * X = B (Transpose) */
/* = 'C': A**H * X = B (Conjugate transpose) */
/* N (input) INTEGER */
/* The order of the matrix A. */
/* NRHS (input) INTEGER */
/* The number of right hand sides, i.e., the number of columns */
/* of the matrix B. NRHS >= 0. */
/* DL (input) COMPLEX array, dimension (N-1) */
/* The (n-1) multipliers that define the matrix L from the */
/* LU factorization of A. */
/* D (input) COMPLEX array, dimension (N) */
/* The n diagonal elements of the upper triangular matrix U from */
/* the LU factorization of A. */
/* DU (input) COMPLEX array, dimension (N-1) */
/* The (n-1) elements of the first super-diagonal of U. */
/* DU2 (input) COMPLEX array, dimension (N-2) */
/* The (n-2) elements of the second super-diagonal of U. */
/* IPIV (input) INTEGER array, dimension (N) */
/* The pivot indices; for 1 <= i <= n, row i of the matrix was */
/* interchanged with row IPIV(i). IPIV(i) will always be either */
/* i or i+1; IPIV(i) = i indicates a row interchange was not */
/* required. */
/* B (input/output) COMPLEX array, dimension (LDB,NRHS) */
/* On entry, the matrix of right hand side vectors B. */
/* On exit, B is overwritten by the solution vectors X. */
/* LDB (input) INTEGER */
/* The leading dimension of the array B. LDB >= max(1,N). */
/* INFO (output) INTEGER */
/* = 0: successful exit */
/* < 0: if INFO = -k, the k-th argument had an illegal value */
/* ===================================================================== */
/* .. Local Scalars .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Parameter adjustments */
--dl;
--d__;
--du;
--du2;
--ipiv;
b_dim1 = *ldb;
b_offset = 1 + b_dim1;
b -= b_offset;
/* Function Body */
*info = 0;
notran = *(unsigned char *)trans == 'N' || *(unsigned char *)trans == 'n';
if (! notran && ! (*(unsigned char *)trans == 'T' || *(unsigned char *)
trans == 't') && ! (*(unsigned char *)trans == 'C' || *(unsigned
char *)trans == 'c')) {
*info = -1;
} else if (*n < 0) {
*info = -2;
} else if (*nrhs < 0) {
*info = -3;
} else if (*ldb < max(*n,1)) {
*info = -10;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("CGTTRS", &i__1);
return 0;
}
/* Quick return if possible */
if (*n == 0 || *nrhs == 0) {
return 0;
}
/* Decode TRANS */
if (notran) {
itrans = 0;
} else if (*(unsigned char *)trans == 'T' || *(unsigned char *)trans ==
't') {
itrans = 1;
} else {
itrans = 2;
}
/* Determine the number of right-hand sides to solve at a time. */
if (*nrhs == 1) {
nb = 1;
} else {
/* Computing MAX */
i__1 = 1, i__2 = ilaenv_(&c__1, "CGTTRS", trans, n, nrhs, &c_n1, &
c_n1);
nb = max(i__1,i__2);
}
if (nb >= *nrhs) {
cgtts2_(&itrans, n, nrhs, &dl[1], &d__[1], &du[1], &du2[1], &ipiv[1],
&b[b_offset], ldb);
} else {
i__1 = *nrhs;
i__2 = nb;
for (j = 1; i__2 < 0 ? j >= i__1 : j <= i__1; j += i__2) {
/* Computing MIN */
i__3 = *nrhs - j + 1;
jb = min(i__3,nb);
cgtts2_(&itrans, n, &jb, &dl[1], &d__[1], &du[1], &du2[1], &ipiv[
1], &b[j * b_dim1 + 1], ldb);
/* L10: */
}
}
/* End of CGTTRS */
return 0;
} /* cgttrs_ */
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