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c5a87f75d6cfbcca5a4b6e2e2f44865c55bf6a89
lammps/lib/linalg/dtrtri.cpp
Axel Kohlmeyer c5a87f75d6 convert linalg library from Fortran to C++
2022-12-28 13:18:38 -05:00

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/* fortran/dtrtri.f -- translated by f2c (version 20200916).
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
*/
#ifdef __cplusplus
extern "C" {
#endif
#include "lmp_f2c.h"
/* Table of constant values */
static integer c__1 = 1;
static integer c_n1 = -1;
static integer c__2 = 2;
static doublereal c_b18 = 1.;
static doublereal c_b22 = -1.;
/* > \brief \b DTRTRI */
/* =========== DOCUMENTATION =========== */
/* Online html documentation available at */
/* http://www.netlib.org/lapack/explore-html/ */
/* > \htmlonly */
/* > Download DTRTRI + dependencies */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dtrtri.
f"> */
/* > [TGZ]</a> */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dtrtri.
f"> */
/* > [ZIP]</a> */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dtrtri.
f"> */
/* > [TXT]</a> */
/* > \endhtmlonly */
/* Definition: */
/* =========== */
/* SUBROUTINE DTRTRI( UPLO, DIAG, N, A, LDA, INFO ) */
/* .. Scalar Arguments .. */
/* CHARACTER DIAG, UPLO */
/* INTEGER INFO, LDA, N */
/* .. */
/* .. Array Arguments .. */
/* DOUBLE PRECISION A( LDA, * ) */
/* .. */
/* > \par Purpose: */
/* ============= */
/* > */
/* > \verbatim */
/* > */
/* > DTRTRI computes the inverse of a real upper or lower triangular */
/* > matrix A. */
/* > */
/* > This is the Level 3 BLAS version of the algorithm. */
/* > \endverbatim */
/* Arguments: */
/* ========== */
/* > \param[in] UPLO */
/* > \verbatim */
/* > UPLO is CHARACTER*1 */
/* > = 'U': A is upper triangular; */
/* > = 'L': A is lower triangular. */
/* > \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,out] A */
/* > \verbatim */
/* > A is DOUBLE PRECISION array, dimension (LDA,N) */
/* > On entry, 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. */
/* > On exit, the (triangular) inverse of the original matrix, in */
/* > the same storage format. */
/* > \endverbatim */
/* > */
/* > \param[in] LDA */
/* > \verbatim */
/* > LDA is INTEGER */
/* > The leading dimension of the array A. LDA >= 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, A(i,i) is exactly zero. The triangular */
/* > matrix is singular and its inverse can not be computed. */
/* > \endverbatim */
/* Authors: */
/* ======== */
/* > \author Univ. of Tennessee */
/* > \author Univ. of California Berkeley */
/* > \author Univ. of Colorado Denver */
/* > \author NAG Ltd. */
/* > \ingroup doubleOTHERcomputational */
/* ===================================================================== */
/* Subroutine */ int dtrtri_(char *uplo, char *diag, integer *n, doublereal *
a, integer *lda, integer *info, ftnlen uplo_len, ftnlen diag_len)
{
/* System generated locals */
address a__1[2];
integer a_dim1, a_offset, i__1, i__2[2], i__3, i__4, i__5;
char ch__1[2];
/* Builtin functions */
/* Subroutine */ int s_cat(char *, char **, integer *, integer *, ftnlen);
/* Local variables */
integer j, jb, nb, nn;
extern logical lsame_(char *, char *, ftnlen, ftnlen);
extern /* Subroutine */ int dtrmm_(char *, char *, char *, char *,
integer *, integer *, doublereal *, doublereal *, integer *,
doublereal *, integer *, ftnlen, ftnlen, ftnlen, ftnlen), dtrsm_(
char *, char *, char *, char *, integer *, integer *, doublereal *
, doublereal *, integer *, doublereal *, integer *, ftnlen,
ftnlen, ftnlen, ftnlen);
logical upper;
extern /* Subroutine */ int dtrti2_(char *, char *, integer *, doublereal
*, integer *, integer *, ftnlen, ftnlen), xerbla_(char *, integer
*, ftnlen);
extern integer ilaenv_(integer *, char *, char *, integer *, integer *,
integer *, integer *, ftnlen, ftnlen);
logical nounit;
/* -- LAPACK computational routine -- */
/* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
/* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
/* .. 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;
/* Function Body */
*info = 0;
upper = lsame_(uplo, (char *)"U", (ftnlen)1, (ftnlen)1);
nounit = lsame_(diag, (char *)"N", (ftnlen)1, (ftnlen)1);
if (! upper && ! lsame_(uplo, (char *)"L", (ftnlen)1, (ftnlen)1)) {
*info = -1;
} else if (! nounit && ! lsame_(diag, (char *)"U", (ftnlen)1, (ftnlen)1)) {
*info = -2;
} else if (*n < 0) {
*info = -3;
} else if (*lda < max(1,*n)) {
*info = -5;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_((char *)"DTRTRI", &i__1, (ftnlen)6);
return 0;
}
/* Quick return if possible */
if (*n == 0) {
return 0;
}
/* Check for singularity if non-unit. */
if (nounit) {
i__1 = *n;
for (*info = 1; *info <= i__1; ++(*info)) {
if (a[*info + *info * a_dim1] == 0.) {
return 0;
}
/* L10: */
}
*info = 0;
}
/* Determine the block size for this environment. */
/* Writing concatenation */
i__2[0] = 1, a__1[0] = uplo;
i__2[1] = 1, a__1[1] = diag;
s_cat(ch__1, a__1, i__2, &c__2, (ftnlen)2);
nb = ilaenv_(&c__1, (char *)"DTRTRI", ch__1, n, &c_n1, &c_n1, &c_n1, (ftnlen)6, (
ftnlen)2);
if (nb <= 1 || nb >= *n) {
/* Use unblocked code */
dtrti2_(uplo, diag, n, &a[a_offset], lda, info, (ftnlen)1, (ftnlen)1);
} else {
/* Use blocked code */
if (upper) {
/* Compute inverse of upper triangular matrix */
i__1 = *n;
i__3 = nb;
for (j = 1; i__3 < 0 ? j >= i__1 : j <= i__1; j += i__3) {
/* Computing MIN */
i__4 = nb, i__5 = *n - j + 1;
jb = min(i__4,i__5);
/* Compute rows 1:j-1 of current block column */
i__4 = j - 1;
dtrmm_((char *)"Left", (char *)"Upper", (char *)"No transpose", diag, &i__4, &jb, &
c_b18, &a[a_offset], lda, &a[j * a_dim1 + 1], lda, (
ftnlen)4, (ftnlen)5, (ftnlen)12, (ftnlen)1);
i__4 = j - 1;
dtrsm_((char *)"Right", (char *)"Upper", (char *)"No transpose", diag, &i__4, &jb, &
c_b22, &a[j + j * a_dim1], lda, &a[j * a_dim1 + 1],
lda, (ftnlen)5, (ftnlen)5, (ftnlen)12, (ftnlen)1);
/* Compute inverse of current diagonal block */
dtrti2_((char *)"Upper", diag, &jb, &a[j + j * a_dim1], lda, info, (
ftnlen)5, (ftnlen)1);
/* L20: */
}
} else {
/* Compute inverse of lower triangular matrix */
nn = (*n - 1) / nb * nb + 1;
i__3 = -nb;
for (j = nn; i__3 < 0 ? j >= 1 : j <= 1; j += i__3) {
/* Computing MIN */
i__1 = nb, i__4 = *n - j + 1;
jb = min(i__1,i__4);
if (j + jb <= *n) {
/* Compute rows j+jb:n of current block column */
i__1 = *n - j - jb + 1;
dtrmm_((char *)"Left", (char *)"Lower", (char *)"No transpose", diag, &i__1, &jb,
&c_b18, &a[j + jb + (j + jb) * a_dim1], lda, &a[j
+ jb + j * a_dim1], lda, (ftnlen)4, (ftnlen)5, (
ftnlen)12, (ftnlen)1);
i__1 = *n - j - jb + 1;
dtrsm_((char *)"Right", (char *)"Lower", (char *)"No transpose", diag, &i__1, &jb,
&c_b22, &a[j + j * a_dim1], lda, &a[j + jb + j *
a_dim1], lda, (ftnlen)5, (ftnlen)5, (ftnlen)12, (
ftnlen)1);
}
/* Compute inverse of current diagonal block */
dtrti2_((char *)"Lower", diag, &jb, &a[j + j * a_dim1], lda, info, (
ftnlen)5, (ftnlen)1);
/* L30: */
}
}
}
return 0;
/* End of DTRTRI */
} /* dtrtri_ */
#ifdef __cplusplus
}
#endif
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