259 lines
7.7 KiB
C++
259 lines
7.7 KiB
C++
/* fortran/dtrti2.f -- translated by f2c (version 20200916).
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You must link the resulting object file with libf2c:
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on Microsoft Windows system, link with libf2c.lib;
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on Linux or Unix systems, link with .../path/to/libf2c.a -lm
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or, if you install libf2c.a in a standard place, with -lf2c -lm
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-- in that order, at the end of the command line, as in
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cc *.o -lf2c -lm
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Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
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http://www.netlib.org/f2c/libf2c.zip
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*/
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include "lmp_f2c.h"
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/* Table of constant values */
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static integer c__1 = 1;
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/* > \brief \b DTRTI2 computes the inverse of a triangular matrix (unblocked algorithm). */
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/* =========== DOCUMENTATION =========== */
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/* Online html documentation available at */
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/* http://www.netlib.org/lapack/explore-html/ */
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/* > \htmlonly */
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/* > Download DTRTI2 + dependencies */
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/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dtrti2.
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f"> */
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/* > [TGZ]</a> */
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/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dtrti2.
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f"> */
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/* > [ZIP]</a> */
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/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dtrti2.
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f"> */
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/* > [TXT]</a> */
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/* > \endhtmlonly */
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/* Definition: */
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/* =========== */
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/* SUBROUTINE DTRTI2( UPLO, DIAG, N, A, LDA, INFO ) */
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/* .. Scalar Arguments .. */
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/* CHARACTER DIAG, UPLO */
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/* INTEGER INFO, LDA, N */
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/* .. */
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/* .. Array Arguments .. */
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/* DOUBLE PRECISION A( LDA, * ) */
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/* .. */
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/* > \par Purpose: */
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/* ============= */
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/* > */
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/* > \verbatim */
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/* > */
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/* > DTRTI2 computes the inverse of a real upper or lower triangular */
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/* > matrix. */
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/* > */
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/* > This is the Level 2 BLAS version of the algorithm. */
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/* > \endverbatim */
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/* Arguments: */
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/* ========== */
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/* > \param[in] UPLO */
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/* > \verbatim */
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/* > UPLO is CHARACTER*1 */
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/* > Specifies whether the matrix A is upper or lower triangular. */
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/* > = 'U': Upper triangular */
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/* > = 'L': Lower triangular */
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/* > \endverbatim */
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/* > */
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/* > \param[in] DIAG */
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/* > \verbatim */
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/* > DIAG is CHARACTER*1 */
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/* > Specifies whether or not the matrix A is unit triangular. */
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/* > = 'N': Non-unit triangular */
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/* > = 'U': Unit triangular */
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/* > \endverbatim */
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/* > */
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/* > \param[in] N */
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/* > \verbatim */
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/* > N is INTEGER */
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/* > The order of the matrix A. N >= 0. */
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/* > \endverbatim */
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/* > */
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/* > \param[in,out] A */
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/* > \verbatim */
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/* > A is DOUBLE PRECISION array, dimension (LDA,N) */
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/* > On entry, the triangular matrix A. If UPLO = 'U', the */
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/* > leading n by n upper triangular part of the array A contains */
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/* > the upper triangular matrix, and the strictly lower */
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/* > triangular part of A is not referenced. If UPLO = 'L', the */
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/* > leading n by n lower triangular part of the array A contains */
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/* > the lower triangular matrix, and the strictly upper */
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/* > triangular part of A is not referenced. If DIAG = 'U', the */
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/* > diagonal elements of A are also not referenced and are */
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/* > assumed to be 1. */
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/* > */
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/* > On exit, the (triangular) inverse of the original matrix, in */
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/* > the same storage format. */
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/* > \endverbatim */
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/* > */
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/* > \param[in] LDA */
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/* > \verbatim */
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/* > LDA is INTEGER */
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/* > The leading dimension of the array A. LDA >= max(1,N). */
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/* > \endverbatim */
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/* > */
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/* > \param[out] INFO */
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/* > \verbatim */
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/* > INFO is INTEGER */
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/* > = 0: successful exit */
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/* > < 0: if INFO = -k, the k-th argument had an illegal value */
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/* > \endverbatim */
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/* Authors: */
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/* ======== */
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/* > \author Univ. of Tennessee */
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/* > \author Univ. of California Berkeley */
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/* > \author Univ. of Colorado Denver */
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/* > \author NAG Ltd. */
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/* > \ingroup doubleOTHERcomputational */
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/* ===================================================================== */
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/* Subroutine */ int dtrti2_(char *uplo, char *diag, integer *n, doublereal *
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a, integer *lda, integer *info, ftnlen uplo_len, ftnlen diag_len)
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{
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/* System generated locals */
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integer a_dim1, a_offset, i__1, i__2;
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/* Local variables */
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integer j;
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doublereal ajj;
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extern /* Subroutine */ int dscal_(integer *, doublereal *, doublereal *,
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integer *);
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extern logical lsame_(char *, char *, ftnlen, ftnlen);
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logical upper;
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extern /* Subroutine */ int dtrmv_(char *, char *, char *, integer *,
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doublereal *, integer *, doublereal *, integer *, ftnlen, ftnlen,
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ftnlen), xerbla_(char *, integer *, ftnlen);
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logical nounit;
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/* -- LAPACK computational routine -- */
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/* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
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/* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
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/* .. Scalar Arguments .. */
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/* .. */
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/* .. Array Arguments .. */
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/* .. */
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/* ===================================================================== */
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/* .. Parameters .. */
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/* .. */
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/* .. Local Scalars .. */
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/* .. */
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/* .. External Functions .. */
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/* .. */
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/* .. External Subroutines .. */
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/* .. */
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/* .. Intrinsic Functions .. */
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/* .. */
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/* .. Executable Statements .. */
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/* Test the input parameters. */
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/* Parameter adjustments */
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a_dim1 = *lda;
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a_offset = 1 + a_dim1;
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a -= a_offset;
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/* Function Body */
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*info = 0;
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upper = lsame_(uplo, (char *)"U", (ftnlen)1, (ftnlen)1);
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nounit = lsame_(diag, (char *)"N", (ftnlen)1, (ftnlen)1);
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if (! upper && ! lsame_(uplo, (char *)"L", (ftnlen)1, (ftnlen)1)) {
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*info = -1;
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} else if (! nounit && ! lsame_(diag, (char *)"U", (ftnlen)1, (ftnlen)1)) {
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*info = -2;
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} else if (*n < 0) {
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*info = -3;
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} else if (*lda < max(1,*n)) {
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*info = -5;
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}
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if (*info != 0) {
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i__1 = -(*info);
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xerbla_((char *)"DTRTI2", &i__1, (ftnlen)6);
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return 0;
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}
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if (upper) {
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/* Compute inverse of upper triangular matrix. */
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i__1 = *n;
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for (j = 1; j <= i__1; ++j) {
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if (nounit) {
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a[j + j * a_dim1] = 1. / a[j + j * a_dim1];
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ajj = -a[j + j * a_dim1];
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} else {
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ajj = -1.;
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}
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/* Compute elements 1:j-1 of j-th column. */
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i__2 = j - 1;
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dtrmv_((char *)"Upper", (char *)"No transpose", diag, &i__2, &a[a_offset], lda, &
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a[j * a_dim1 + 1], &c__1, (ftnlen)5, (ftnlen)12, (ftnlen)
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1);
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i__2 = j - 1;
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dscal_(&i__2, &ajj, &a[j * a_dim1 + 1], &c__1);
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/* L10: */
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}
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} else {
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/* Compute inverse of lower triangular matrix. */
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for (j = *n; j >= 1; --j) {
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if (nounit) {
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a[j + j * a_dim1] = 1. / a[j + j * a_dim1];
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ajj = -a[j + j * a_dim1];
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} else {
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ajj = -1.;
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}
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if (j < *n) {
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/* Compute elements j+1:n of j-th column. */
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i__1 = *n - j;
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dtrmv_((char *)"Lower", (char *)"No transpose", diag, &i__1, &a[j + 1 + (j +
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1) * a_dim1], lda, &a[j + 1 + j * a_dim1], &c__1, (
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ftnlen)5, (ftnlen)12, (ftnlen)1);
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i__1 = *n - j;
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dscal_(&i__1, &ajj, &a[j + 1 + j * a_dim1], &c__1);
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}
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/* L20: */
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}
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}
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return 0;
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/* End of DTRTI2 */
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} /* dtrti2_ */
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#ifdef __cplusplus
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}
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#endif
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