184 lines
5.3 KiB
C
184 lines
5.3 KiB
C
/* dtrtrs.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 "clapack.h"
|
|
|
|
|
|
/* Table of constant values */
|
|
|
|
static doublereal c_b12 = 1.;
|
|
|
|
/* Subroutine */ int dtrtrs_(char *uplo, char *trans, char *diag, integer *n,
|
|
integer *nrhs, doublereal *a, integer *lda, doublereal *b, integer *
|
|
ldb, integer *info)
|
|
{
|
|
/* System generated locals */
|
|
integer a_dim1, a_offset, b_dim1, b_offset, i__1;
|
|
|
|
/* Local variables */
|
|
extern logical lsame_(char *, char *);
|
|
extern /* Subroutine */ int dtrsm_(char *, char *, char *, char *,
|
|
integer *, integer *, doublereal *, doublereal *, integer *,
|
|
doublereal *, integer *), xerbla_(
|
|
char *, integer *);
|
|
logical nounit;
|
|
|
|
|
|
/* -- LAPACK routine (version 3.2) -- */
|
|
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
|
|
/* November 2006 */
|
|
|
|
/* .. Scalar Arguments .. */
|
|
/* .. */
|
|
/* .. Array Arguments .. */
|
|
/* .. */
|
|
|
|
/* Purpose */
|
|
/* ======= */
|
|
|
|
/* DTRTRS solves a triangular system of the form */
|
|
|
|
/* A * X = B or A**T * 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. */
|
|
|
|
/* Arguments */
|
|
/* ========= */
|
|
|
|
/* UPLO (input) CHARACTER*1 */
|
|
/* = 'U': A is upper triangular; */
|
|
/* = 'L': A is lower triangular. */
|
|
|
|
/* 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 = Transpose) */
|
|
|
|
/* DIAG (input) CHARACTER*1 */
|
|
/* = 'N': A is non-unit triangular; */
|
|
/* = 'U': A is unit triangular. */
|
|
|
|
/* 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) DOUBLE PRECISION 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. */
|
|
|
|
/* LDA (input) INTEGER */
|
|
/* The leading dimension of the array A. LDA >= max(1,N). */
|
|
|
|
/* B (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS) */
|
|
/* On entry, the right hand side matrix B. */
|
|
/* On exit, if INFO = 0, 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 */
|
|
/* > 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. */
|
|
|
|
/* ===================================================================== */
|
|
|
|
/* .. 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_("DTRTRS", &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)) {
|
|
if (a[*info + *info * a_dim1] == 0.) {
|
|
return 0;
|
|
}
|
|
/* L10: */
|
|
}
|
|
}
|
|
*info = 0;
|
|
|
|
/* Solve A * x = b or A' * x = b. */
|
|
|
|
dtrsm_("Left", uplo, trans, diag, n, nrhs, &c_b12, &a[a_offset], lda, &b[
|
|
b_offset], ldb);
|
|
|
|
return 0;
|
|
|
|
/* End of DTRTRS */
|
|
|
|
} /* dtrtrs_ */
|