/* zpotf2.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 "f2c.h"
#include "blaswrap.h"
/* Table of constant values */
static doublecomplex c_b1 = {1.,0.};
static integer c__1 = 1;
/* Subroutine */ int zpotf2_(char *uplo, integer *n, doublecomplex *a,
integer *lda, integer *info)
{
/* System generated locals */
integer a_dim1, a_offset, i__1, i__2, i__3;
doublereal d__1;
doublecomplex z__1, z__2;
/* Builtin functions */
double sqrt(doublereal);
/* Local variables */
integer j;
doublereal ajj;
extern logical lsame_(char *, char *);
extern /* Double Complex */ VOID zdotc_(doublecomplex *, integer *,
doublecomplex *, integer *, doublecomplex *, integer *);
extern /* Subroutine */ int zgemv_(char *, integer *, integer *,
doublecomplex *, doublecomplex *, integer *, doublecomplex *,
integer *, doublecomplex *, doublecomplex *, integer *);
logical upper;
extern logical disnan_(doublereal *);
extern /* Subroutine */ int xerbla_(char *, integer *), zdscal_(
integer *, doublereal *, doublecomplex *, integer *), zlacgv_(
integer *, doublecomplex *, integer *);
/* -- LAPACK routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* ZPOTF2 computes the Cholesky factorization of a complex Hermitian */
/* positive definite matrix A. */
/* The factorization has the form */
/* A = U' * U , if UPLO = 'U', or */
/* A = L * L', 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. */
/* Arguments */
/* ========= */
/* UPLO (input) CHARACTER*1 */
/* Specifies whether the upper or lower triangular part of the */
/* Hermitian matrix A is stored. */
/* = 'U': Upper triangular */
/* = 'L': Lower triangular */
/* N (input) INTEGER */
/* The order of the matrix A. N >= 0. */
/* A (input/output) COMPLEX*16 array, dimension (LDA,N) */
/* On entry, the Hermitian 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'*U or A = L*L'. */
/* LDA (input) INTEGER */
/* The leading dimension of the array A. LDA >= max(1,N). */
/* INFO (output) 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. */
/* ===================================================================== */
/* .. 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, "U");
if (! upper && ! lsame_(uplo, "L")) {
*info = -1;
} else if (*n < 0) {
*info = -2;
} else if (*lda < max(1,*n)) {
*info = -4;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("ZPOTF2", &i__1);
return 0;
}
/* Quick return if possible */
if (*n == 0) {
return 0;
}
if (upper) {
/* Compute the Cholesky factorization A = U'*U. */
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
/* Compute U(J,J) and test for non-positive-definiteness. */
i__2 = j + j * a_dim1;
d__1 = a[i__2].r;
i__3 = j - 1;
zdotc_(&z__2, &i__3, &a[j * a_dim1 + 1], &c__1, &a[j * a_dim1 + 1]
, &c__1);
z__1.r = d__1 - z__2.r, z__1.i = -z__2.i;
ajj = z__1.r;
if (ajj <= 0. || disnan_(&ajj)) {
i__2 = j + j * a_dim1;
a[i__2].r = ajj, a[i__2].i = 0.;
goto L30;
}
ajj = sqrt(ajj);
i__2 = j + j * a_dim1;
a[i__2].r = ajj, a[i__2].i = 0.;
/* Compute elements J+1:N of row J. */
if (j < *n) {
i__2 = j - 1;
zlacgv_(&i__2, &a[j * a_dim1 + 1], &c__1);
i__2 = j - 1;
i__3 = *n - j;
z__1.r = -1., z__1.i = -0.;
zgemv_("Transpose", &i__2, &i__3, &z__1, &a[(j + 1) * a_dim1
+ 1], lda, &a[j * a_dim1 + 1], &c__1, &c_b1, &a[j + (
j + 1) * a_dim1], lda);
i__2 = j - 1;
zlacgv_(&i__2, &a[j * a_dim1 + 1], &c__1);
i__2 = *n - j;
d__1 = 1. / ajj;
zdscal_(&i__2, &d__1, &a[j + (j + 1) * a_dim1], lda);
}
/* L10: */
}
} else {
/* Compute the Cholesky factorization A = L*L'. */
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
/* Compute L(J,J) and test for non-positive-definiteness. */
i__2 = j + j * a_dim1;
d__1 = a[i__2].r;
i__3 = j - 1;
zdotc_(&z__2, &i__3, &a[j + a_dim1], lda, &a[j + a_dim1], lda);
z__1.r = d__1 - z__2.r, z__1.i = -z__2.i;
ajj = z__1.r;
if (ajj <= 0. || disnan_(&ajj)) {
i__2 = j + j * a_dim1;
a[i__2].r = ajj, a[i__2].i = 0.;
goto L30;
}
ajj = sqrt(ajj);
i__2 = j + j * a_dim1;
a[i__2].r = ajj, a[i__2].i = 0.;
/* Compute elements J+1:N of column J. */
if (j < *n) {
i__2 = j - 1;
zlacgv_(&i__2, &a[j + a_dim1], lda);
i__2 = *n - j;
i__3 = j - 1;
z__1.r = -1., z__1.i = -0.;
zgemv_("No transpose", &i__2, &i__3, &z__1, &a[j + 1 + a_dim1]
, lda, &a[j + a_dim1], lda, &c_b1, &a[j + 1 + j *
a_dim1], &c__1);
i__2 = j - 1;
zlacgv_(&i__2, &a[j + a_dim1], lda);
i__2 = *n - j;
d__1 = 1. / ajj;
zdscal_(&i__2, &d__1, &a[j + 1 + j * a_dim1], &c__1);
}
/* L20: */
}
}
goto L40;
L30:
*info = j;
L40:
return 0;
/* End of ZPOTF2 */
} /* zpotf2_ */