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/* ../netlib/ctrtrs.f -- translated by f2c (version 20100827). 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 "FLA_f2c.h" /* Table of constant values */
static complex c_b2 =
{
1.f,0.f
}
;
/* > \brief \b CTRTRS */
/* =========== DOCUMENTATION =========== */
/* Online html documentation available at */
/* http://www.netlib.org/lapack/explore-html/ */
/* > \htmlonly */
/* > Download CTRTRS + dependencies */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/ctrtrs. f"> */
/* > [TGZ]</a> */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/ctrtrs. f"> */
/* > [ZIP]</a> */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/ctrtrs. f"> */
/* > [TXT]</a> */
/* > \endhtmlonly */
/* Definition: */
/* =========== */
/* SUBROUTINE CTRTRS( UPLO, TRANS, DIAG, N, NRHS, A, LDA, B, LDB, */
/* INFO ) */
/* .. Scalar Arguments .. */
/* CHARACTER DIAG, TRANS, UPLO */
/* INTEGER INFO, LDA, LDB, N, NRHS */
/* .. */
/* .. Array Arguments .. */
/* COMPLEX A( LDA, * ), B( LDB, * ) */
/* .. */
/* > \par Purpose: */
/* ============= */
/* > */
/* > \verbatim */
/* > */
/* > CTRTRS solves a triangular system of the form */
/* > */
/* > A * X = B, A**T * X = B, or A**H * X = B, */
/* > */
/* > where A is a triangular matrix of order N, and B is an N-by-NRHS */
/* > matrix. A check is made to verify that A is nonsingular. */
/* > \endverbatim */
/* Arguments: */
/* ========== */
/* > \param[in] UPLO */
/* > \verbatim */
/* > UPLO is CHARACTER*1 */
/* > = 'U': A is upper triangular;
*/
/* > = 'L': A is lower triangular. */
/* > \endverbatim */
/* > */
/* > \param[in] TRANS */
/* > \verbatim */
/* > TRANS is 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) */
/* > \endverbatim */
/* > */
/* > \param[in] DIAG */
/* > \verbatim */
/* > DIAG is CHARACTER*1 */
/* > = 'N': A is non-unit triangular;
*/
/* > = 'U': A is unit triangular. */
/* > \endverbatim */
/* > */
/* > \param[in] N */
/* > \verbatim */
/* > N is INTEGER */
/* > The order of the matrix A. N >= 0. */
/* > \endverbatim */
/* > */
/* > \param[in] NRHS */
/* > \verbatim */
/* > NRHS is INTEGER */
/* > The number of right hand sides, i.e., the number of columns */
/* > of the matrix B. NRHS >= 0. */
/* > \endverbatim */
/* > */
/* > \param[in] A */
/* > \verbatim */
/* > A is COMPLEX array, dimension (LDA,N) */
/* > The triangular matrix A. If UPLO = 'U', the leading N-by-N */
/* > upper triangular part of the array A contains the upper */
/* > triangular matrix, and the strictly lower triangular part of */
/* > A is not referenced. If UPLO = 'L', the leading N-by-N lower */
/* > triangular part of the array A contains the lower triangular */
/* > matrix, and the strictly upper triangular part of A is not */
/* > referenced. If DIAG = 'U', the diagonal elements of A are */
/* > also not referenced and are assumed to be 1. */
/* > \endverbatim */
/* > */
/* > \param[in] LDA */
/* > \verbatim */
/* > LDA is INTEGER */
/* > The leading dimension of the array A. LDA >= max(1,N). */
/* > \endverbatim */
/* > */
/* > \param[in,out] B */
/* > \verbatim */
/* > B is COMPLEX array, dimension (LDB,NRHS) */
/* > On entry, the right hand side matrix B. */
/* > On exit, if INFO = 0, the solution matrix X. */
/* > \endverbatim */
/* > */
/* > \param[in] LDB */
/* > \verbatim */
/* > LDB is INTEGER */
/* > The leading dimension of the array B. LDB >= max(1,N). */
/* > \endverbatim */
/* > */
/* > \param[out] INFO */
/* > \verbatim */
/* > INFO is INTEGER */
/* > = 0: successful exit */
/* > < 0: if INFO = -i, the i-th argument had an illegal value */
/* > > 0: if INFO = i, the i-th diagonal element of A is zero, */
/* > indicating that the matrix is singular and the solutions */
/* > X have not been computed. */
/* > \endverbatim */
/* Authors: */
/* ======== */
/* > \author Univ. of Tennessee */
/* > \author Univ. of California Berkeley */
/* > \author Univ. of Colorado Denver */
/* > \author NAG Ltd. */
/* > \date November 2011 */
/* > \ingroup complexOTHERcomputational */
/* ===================================================================== */
/* Subroutine */
int ctrtrs_(char *uplo, char *trans, char *diag, integer *n, integer *nrhs, complex *a, integer *lda, complex *b, integer *ldb, integer *info)
{
/* System generated locals */
integer a_dim1, a_offset, b_dim1, b_offset, i__1, i__2;
/* Local variables */
extern logical lsame_(char *, char *);
extern /* Subroutine */
int ctrsm_(char *, char *, char *, char *, integer *, integer *, complex *, complex *, integer *, complex *, integer *), xerbla_(char *, integer *);
logical nounit;
/* -- LAPACK computational routine (version 3.4.0) -- */
/* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
/* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
/* November 2011 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Test the input parameters. */
/* Parameter adjustments */
a_dim1 = *lda;
a_offset = 1 + a_dim1;
a -= a_offset;
b_dim1 = *ldb;
b_offset = 1 + b_dim1;
b -= b_offset;
/* Function Body */
*info = 0;
nounit = lsame_(diag, "N");
if (! lsame_(uplo, "U") && ! lsame_(uplo, "L"))
{
*info = -1;
}
else if (! lsame_(trans, "N") && ! lsame_(trans, "T") && ! lsame_(trans, "C"))
{
*info = -2;
}
else if (! nounit && ! lsame_(diag, "U"))
{
*info = -3;
}
else if (*n < 0)
{
*info = -4;
}
else if (*nrhs < 0)
{
*info = -5;
}
else if (*lda < max(1,*n))
{
*info = -7;
}
else if (*ldb < max(1,*n))
{
*info = -9;
}
if (*info != 0)
{
i__1 = -(*info);
xerbla_("CTRTRS", &i__1);
return 0;
}
/* Quick return if possible */
if (*n == 0)
{
return 0;
}
/* Check for singularity. */
if (nounit)
{
i__1 = *n;
for (*info = 1;
*info <= i__1;
++(*info))
{
i__2 = *info + *info * a_dim1;
if (a[i__2].r == 0.f && a[i__2].i == 0.f)
{
return 0;
}
/* L10: */
}
}
*info = 0;
/* Solve A * x = b, A**T * x = b, or A**H * x = b. */
ctrsm_("Left", uplo, trans, diag, n, nrhs, &c_b2, &a[a_offset], lda, &b[ b_offset], ldb);
return 0;
/* End of CTRTRS */
}
/* ctrtrs_ */
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