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

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/* fortran/zpptrf.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_b16 = -1.;
/* > \brief \b ZPPTRF */
/* =========== DOCUMENTATION =========== */
/* Online html documentation available at */
/* http://www.netlib.org/lapack/explore-html/ */
/* > \htmlonly */
/* > Download ZPPTRF + dependencies */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/zpptrf.
f"> */
/* > [TGZ]</a> */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/zpptrf.
f"> */
/* > [ZIP]</a> */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/zpptrf.
f"> */
/* > [TXT]</a> */
/* > \endhtmlonly */
/* Definition: */
/* =========== */
/* SUBROUTINE ZPPTRF( UPLO, N, AP, INFO ) */
/* .. Scalar Arguments .. */
/* CHARACTER UPLO */
/* INTEGER INFO, N */
/* .. */
/* .. Array Arguments .. */
/* COMPLEX*16 AP( * ) */
/* .. */
/* > \par Purpose: */
/* ============= */
/* > */
/* > \verbatim */
/* > */
/* > ZPPTRF computes the Cholesky factorization of a complex Hermitian */
/* > positive definite matrix A stored in packed format. */
/* > */
/* > The factorization has the form */
/* > A = U**H * U, if UPLO = 'U', or */
/* > A = L * L**H, if UPLO = 'L', */
/* > where U is an upper triangular matrix and L is lower triangular. */
/* > \endverbatim */
/* Arguments: */
/* ========== */
/* > \param[in] UPLO */
/* > \verbatim */
/* > UPLO is CHARACTER*1 */
/* > = 'U': Upper triangle of A is stored; */
/* > = 'L': Lower triangle of A is stored. */
/* > \endverbatim */
/* > */
/* > \param[in] N */
/* > \verbatim */
/* > N is INTEGER */
/* > The order of the matrix A. N >= 0. */
/* > \endverbatim */
/* > */
/* > \param[in,out] AP */
/* > \verbatim */
/* > AP is COMPLEX*16 array, dimension (N*(N+1)/2) */
/* > On entry, the upper or lower triangle of the Hermitian matrix */
/* > A, packed columnwise in a linear array. The j-th column of A */
/* > is stored in the array AP as follows: */
/* > if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j; */
/* > if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n. */
/* > See below for further details. */
/* > */
/* > On exit, if INFO = 0, the triangular factor U or L from the */
/* > Cholesky factorization A = U**H*U or A = L*L**H, in the same */
/* > storage format as A. */
/* > \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 leading minor of order i 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 complex16OTHERcomputational */
/* > \par Further Details: */
/* ===================== */
/* > */
/* > \verbatim */
/* > */
/* > The packed storage scheme is illustrated by the following example */
/* > when N = 4, UPLO = 'U': */
/* > */
/* > Two-dimensional storage of the Hermitian matrix A: */
/* > */
/* > a11 a12 a13 a14 */
/* > a22 a23 a24 */
/* > a33 a34 (aij = conjg(aji)) */
/* > a44 */
/* > */
/* > Packed storage of the upper triangle of A: */
/* > */
/* > AP = [ a11, a12, a22, a13, a23, a33, a14, a24, a34, a44 ] */
/* > \endverbatim */
/* > */
/* ===================================================================== */
/* Subroutine */ int zpptrf_(char *uplo, integer *n, doublecomplex *ap,
integer *info, ftnlen uplo_len)
{
/* System generated locals */
integer i__1, i__2, i__3;
doublereal d__1;
doublecomplex z__1;
/* Builtin functions */
double sqrt(doublereal);
/* Local variables */
integer j, jc, jj;
doublereal ajj;
extern /* Subroutine */ int zhpr_(char *, integer *, doublereal *,
doublecomplex *, integer *, doublecomplex *, ftnlen);
extern logical lsame_(char *, char *, ftnlen, ftnlen);
extern /* Double Complex */ VOID zdotc_(doublecomplex *, integer *,
doublecomplex *, integer *, doublecomplex *, integer *);
logical upper;
extern /* Subroutine */ int ztpsv_(char *, char *, char *, integer *,
doublecomplex *, doublecomplex *, integer *, ftnlen, ftnlen,
ftnlen), xerbla_(char *, integer *, ftnlen), zdscal_(integer *,
doublereal *, doublecomplex *, integer *);
/* -- 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 */
--ap;
/* 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;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_((char *)"ZPPTRF", &i__1, (ftnlen)6);
return 0;
}
/* Quick return if possible */
if (*n == 0) {
return 0;
}
if (upper) {
/* Compute the Cholesky factorization A = U**H * U. */
jj = 0;
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
jc = jj + 1;
jj += j;
/* Compute elements 1:J-1 of column J. */
if (j > 1) {
i__2 = j - 1;
ztpsv_((char *)"Upper", (char *)"Conjugate transpose", (char *)"Non-unit", &i__2, &ap[
1], &ap[jc], &c__1, (ftnlen)5, (ftnlen)19, (ftnlen)8);
}
/* Compute U(J,J) and test for non-positive-definiteness. */
i__2 = jj;
i__3 = j - 1;
zdotc_(&z__1, &i__3, &ap[jc], &c__1, &ap[jc], &c__1);
ajj = ap[i__2].r - z__1.r;
if (ajj <= 0.) {
i__2 = jj;
ap[i__2].r = ajj, ap[i__2].i = 0.;
goto L30;
}
i__2 = jj;
d__1 = sqrt(ajj);
ap[i__2].r = d__1, ap[i__2].i = 0.;
/* L10: */
}
} else {
/* Compute the Cholesky factorization A = L * L**H. */
jj = 1;
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
/* Compute L(J,J) and test for non-positive-definiteness. */
i__2 = jj;
ajj = ap[i__2].r;
if (ajj <= 0.) {
i__2 = jj;
ap[i__2].r = ajj, ap[i__2].i = 0.;
goto L30;
}
ajj = sqrt(ajj);
i__2 = jj;
ap[i__2].r = ajj, ap[i__2].i = 0.;
/* Compute elements J+1:N of column J and update the trailing */
/* submatrix. */
if (j < *n) {
i__2 = *n - j;
d__1 = 1. / ajj;
zdscal_(&i__2, &d__1, &ap[jj + 1], &c__1);
i__2 = *n - j;
zhpr_((char *)"Lower", &i__2, &c_b16, &ap[jj + 1], &c__1, &ap[jj + *n
- j + 1], (ftnlen)5);
jj = jj + *n - j + 1;
}
/* L20: */
}
}
goto L40;
L30:
*info = j;
L40:
return 0;
/* End of ZPPTRF */
} /* zpptrf_ */
#ifdef __cplusplus
}
#endif
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