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1e8b2ad5a07fd32e63b55d7d52e1264829b96bb4
lammps/lib/linalg/dpotf2.cpp
Axel Kohlmeyer 1e8b2ad5a0 whitespace fixes
2022-12-28 13:48:43 -05:00

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/* fortran/dpotf2.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 doublereal c_b10 = -1.;
static doublereal c_b12 = 1.;
/* > \brief \b DPOTF2 computes the Cholesky factorization of a symmetric/Hermitian positive definite matrix (u
nblocked algorithm). */
/* =========== DOCUMENTATION =========== */
/* Online html documentation available at */
/* http://www.netlib.org/lapack/explore-html/ */
/* > \htmlonly */
/* > Download DPOTF2 + dependencies */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dpotf2.
f"> */
/* > [TGZ]</a> */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dpotf2.
f"> */
/* > [ZIP]</a> */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dpotf2.
f"> */
/* > [TXT]</a> */
/* > \endhtmlonly */
/* Definition: */
/* =========== */
/* SUBROUTINE DPOTF2( UPLO, N, A, LDA, INFO ) */
/* .. Scalar Arguments .. */
/* CHARACTER UPLO */
/* INTEGER INFO, LDA, N */
/* .. */
/* .. Array Arguments .. */
/* DOUBLE PRECISION A( LDA, * ) */
/* .. */
/* > \par Purpose: */
/* ============= */
/* > */
/* > \verbatim */
/* > */
/* > DPOTF2 computes the Cholesky factorization of a real symmetric */
/* > positive definite matrix A. */
/* > */
/* > The factorization has the form */
/* > A = U**T * U , if UPLO = 'U', or */
/* > A = L * L**T, if UPLO = 'L', */
/* > where U is an upper triangular matrix and L is lower triangular. */
/* > */
/* > This is the unblocked version of the algorithm, calling Level 2 BLAS. */
/* > \endverbatim */
/* Arguments: */
/* ========== */
/* > \param[in] UPLO */
/* > \verbatim */
/* > UPLO is CHARACTER*1 */
/* > Specifies whether the upper or lower triangular part of the */
/* > symmetric matrix A is stored. */
/* > = 'U': Upper triangular */
/* > = 'L': Lower 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 symmetric matrix A. If UPLO = 'U', the leading */
/* > n by n upper triangular part of A contains the upper */
/* > triangular part of the matrix A, and the strictly lower */
/* > triangular part of A is not referenced. If UPLO = 'L', the */
/* > leading n by n lower triangular part of A contains the lower */
/* > triangular part of the matrix A, and the strictly upper */
/* > triangular part of A is not referenced. */
/* > */
/* > On exit, if INFO = 0, the factor U or L from the Cholesky */
/* > factorization A = U**T *U or A = L*L**T. */
/* > \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 = -k, the k-th argument had an illegal value */
/* > > 0: if INFO = k, the leading minor of order k is not */
/* > positive definite, and the factorization could not be */
/* > completed. */
/* > \endverbatim */
/* Authors: */
/* ======== */
/* > \author Univ. of Tennessee */
/* > \author Univ. of California Berkeley */
/* > \author Univ. of Colorado Denver */
/* > \author NAG Ltd. */
/* > \ingroup doublePOcomputational */
/* ===================================================================== */
/* Subroutine */ int dpotf2_(char *uplo, integer *n, doublereal *a, integer *
lda, integer *info, ftnlen uplo_len)
{
/* System generated locals */
integer a_dim1, a_offset, i__1, i__2, i__3;
doublereal d__1;
/* Builtin functions */
double sqrt(doublereal);
/* Local variables */
integer j;
doublereal ajj;
extern doublereal ddot_(integer *, doublereal *, integer *, doublereal *,
integer *);
extern /* Subroutine */ int dscal_(integer *, doublereal *, doublereal *,
integer *);
extern logical lsame_(char *, char *, ftnlen, ftnlen);
extern /* Subroutine */ int dgemv_(char *, integer *, integer *,
doublereal *, doublereal *, integer *, doublereal *, integer *,
doublereal *, doublereal *, integer *, ftnlen);
logical upper;
extern logical disnan_(doublereal *);
extern /* Subroutine */ int xerbla_(char *, integer *, ftnlen);
/* -- 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);
if (! upper && ! lsame_(uplo, (char *)"L", (ftnlen)1, (ftnlen)1)) {
*info = -1;
} else if (*n < 0) {
*info = -2;
} else if (*lda < max(1,*n)) {
*info = -4;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_((char *)"DPOTF2", &i__1, (ftnlen)6);
return 0;
}
/* Quick return if possible */
if (*n == 0) {
return 0;
}
if (upper) {
/* Compute the Cholesky factorization A = U**T *U. */
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
/* Compute U(J,J) and test for non-positive-definiteness. */
i__2 = j - 1;
ajj = a[j + j * a_dim1] - ddot_(&i__2, &a[j * a_dim1 + 1], &c__1,
&a[j * a_dim1 + 1], &c__1);
if (ajj <= 0. || disnan_(&ajj)) {
a[j + j * a_dim1] = ajj;
goto L30;
}
ajj = sqrt(ajj);
a[j + j * a_dim1] = ajj;
/* Compute elements J+1:N of row J. */
if (j < *n) {
i__2 = j - 1;
i__3 = *n - j;
dgemv_((char *)"Transpose", &i__2, &i__3, &c_b10, &a[(j + 1) * a_dim1
+ 1], lda, &a[j * a_dim1 + 1], &c__1, &c_b12, &a[j + (
j + 1) * a_dim1], lda, (ftnlen)9);
i__2 = *n - j;
d__1 = 1. / ajj;
dscal_(&i__2, &d__1, &a[j + (j + 1) * a_dim1], lda);
}
/* L10: */
}
} else {
/* Compute the Cholesky factorization A = L*L**T. */
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
/* Compute L(J,J) and test for non-positive-definiteness. */
i__2 = j - 1;
ajj = a[j + j * a_dim1] - ddot_(&i__2, &a[j + a_dim1], lda, &a[j
+ a_dim1], lda);
if (ajj <= 0. || disnan_(&ajj)) {
a[j + j * a_dim1] = ajj;
goto L30;
}
ajj = sqrt(ajj);
a[j + j * a_dim1] = ajj;
/* Compute elements J+1:N of column J. */
if (j < *n) {
i__2 = *n - j;
i__3 = j - 1;
dgemv_((char *)"No transpose", &i__2, &i__3, &c_b10, &a[j + 1 +
a_dim1], lda, &a[j + a_dim1], lda, &c_b12, &a[j + 1 +
j * a_dim1], &c__1, (ftnlen)12);
i__2 = *n - j;
d__1 = 1. / ajj;
dscal_(&i__2, &d__1, &a[j + 1 + j * a_dim1], &c__1);
}
/* L20: */
}
}
goto L40;
L30:
*info = j;
L40:
return 0;
/* End of DPOTF2 */
} /* dpotf2_ */
#ifdef __cplusplus
}
#endif
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