/* zptts2.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"
/* Subroutine */ int zptts2_(integer *iuplo, integer *n, integer *nrhs,
doublereal *d__, doublecomplex *e, doublecomplex *b, integer *ldb)
{
/* System generated locals */
integer b_dim1, b_offset, i__1, i__2, i__3, i__4, i__5, i__6;
doublereal d__1;
doublecomplex z__1, z__2, z__3, z__4;
/* Builtin functions */
void d_cnjg(doublecomplex *, doublecomplex *);
/* Local variables */
integer i__, j;
extern /* Subroutine */ int zdscal_(integer *, doublereal *,
doublecomplex *, integer *);
/* -- LAPACK routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* ZPTTS2 solves a tridiagonal system of the form */
/* A * X = B */
/* using the factorization A = U'*D*U or A = L*D*L' computed by ZPTTRF. */
/* D is a diagonal matrix specified in the vector D, U (or L) is a unit */
/* bidiagonal matrix whose superdiagonal (subdiagonal) is specified in */
/* the vector E, and X and B are N by NRHS matrices. */
/* Arguments */
/* ========= */
/* IUPLO (input) INTEGER */
/* Specifies the form of the factorization and whether the */
/* vector E is the superdiagonal of the upper bidiagonal factor */
/* U or the subdiagonal of the lower bidiagonal factor L. */
/* = 1: A = U'*D*U, E is the superdiagonal of U */
/* = 0: A = L*D*L', E is the subdiagonal of L */
/* N (input) INTEGER */
/* The order of the tridiagonal matrix A. N >= 0. */
/* NRHS (input) INTEGER */
/* The number of right hand sides, i.e., the number of columns */
/* of the matrix B. NRHS >= 0. */
/* D (input) DOUBLE PRECISION array, dimension (N) */
/* The n diagonal elements of the diagonal matrix D from the */
/* factorization A = U'*D*U or A = L*D*L'. */
/* E (input) COMPLEX*16 array, dimension (N-1) */
/* If IUPLO = 1, the (n-1) superdiagonal elements of the unit */
/* bidiagonal factor U from the factorization A = U'*D*U. */
/* If IUPLO = 0, the (n-1) subdiagonal elements of the unit */
/* bidiagonal factor L from the factorization A = L*D*L'. */
/* B (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS) */
/* On entry, the right hand side vectors B for the system of */
/* linear equations. */
/* On exit, the solution vectors, X. */
/* LDB (input) INTEGER */
/* The leading dimension of the array B. LDB >= max(1,N). */
/* ===================================================================== */
/* .. Local Scalars .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Quick return if possible */
/* Parameter adjustments */
--d__;
--e;
b_dim1 = *ldb;
b_offset = 1 + b_dim1;
b -= b_offset;
/* Function Body */
if (*n <= 1) {
if (*n == 1) {
d__1 = 1. / d__[1];
zdscal_(nrhs, &d__1, &b[b_offset], ldb);
}
return 0;
}
if (*iuplo == 1) {
/* Solve A * X = B using the factorization A = U'*D*U, */
/* overwriting each right hand side vector with its solution. */
if (*nrhs <= 2) {
j = 1;
L10:
/* Solve U' * x = b. */
i__1 = *n;
for (i__ = 2; i__ <= i__1; ++i__) {
i__2 = i__ + j * b_dim1;
i__3 = i__ + j * b_dim1;
i__4 = i__ - 1 + j * b_dim1;
d_cnjg(&z__3, &e[i__ - 1]);
z__2.r = b[i__4].r * z__3.r - b[i__4].i * z__3.i, z__2.i = b[
i__4].r * z__3.i + b[i__4].i * z__3.r;
z__1.r = b[i__3].r - z__2.r, z__1.i = b[i__3].i - z__2.i;
b[i__2].r = z__1.r, b[i__2].i = z__1.i;
/* L20: */
}
/* Solve D * U * x = b. */
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
i__2 = i__ + j * b_dim1;
i__3 = i__ + j * b_dim1;
i__4 = i__;
z__1.r = b[i__3].r / d__[i__4], z__1.i = b[i__3].i / d__[i__4]
;
b[i__2].r = z__1.r, b[i__2].i = z__1.i;
/* L30: */
}
for (i__ = *n - 1; i__ >= 1; --i__) {
i__1 = i__ + j * b_dim1;
i__2 = i__ + j * b_dim1;
i__3 = i__ + 1 + j * b_dim1;
i__4 = i__;
z__2.r = b[i__3].r * e[i__4].r - b[i__3].i * e[i__4].i,
z__2.i = b[i__3].r * e[i__4].i + b[i__3].i * e[i__4]
.r;
z__1.r = b[i__2].r - z__2.r, z__1.i = b[i__2].i - z__2.i;
b[i__1].r = z__1.r, b[i__1].i = z__1.i;
/* L40: */
}
if (j < *nrhs) {
++j;
goto L10;
}
} else {
i__1 = *nrhs;
for (j = 1; j <= i__1; ++j) {
/* Solve U' * x = b. */
i__2 = *n;
for (i__ = 2; i__ <= i__2; ++i__) {
i__3 = i__ + j * b_dim1;
i__4 = i__ + j * b_dim1;
i__5 = i__ - 1 + j * b_dim1;
d_cnjg(&z__3, &e[i__ - 1]);
z__2.r = b[i__5].r * z__3.r - b[i__5].i * z__3.i, z__2.i =
b[i__5].r * z__3.i + b[i__5].i * z__3.r;
z__1.r = b[i__4].r - z__2.r, z__1.i = b[i__4].i - z__2.i;
b[i__3].r = z__1.r, b[i__3].i = z__1.i;
/* L50: */
}
/* Solve D * U * x = b. */
i__2 = *n + j * b_dim1;
i__3 = *n + j * b_dim1;
i__4 = *n;
z__1.r = b[i__3].r / d__[i__4], z__1.i = b[i__3].i / d__[i__4]
;
b[i__2].r = z__1.r, b[i__2].i = z__1.i;
for (i__ = *n - 1; i__ >= 1; --i__) {
i__2 = i__ + j * b_dim1;
i__3 = i__ + j * b_dim1;
i__4 = i__;
z__2.r = b[i__3].r / d__[i__4], z__2.i = b[i__3].i / d__[
i__4];
i__5 = i__ + 1 + j * b_dim1;
i__6 = i__;
z__3.r = b[i__5].r * e[i__6].r - b[i__5].i * e[i__6].i,
z__3.i = b[i__5].r * e[i__6].i + b[i__5].i * e[
i__6].r;
z__1.r = z__2.r - z__3.r, z__1.i = z__2.i - z__3.i;
b[i__2].r = z__1.r, b[i__2].i = z__1.i;
/* L60: */
}
/* L70: */
}
}
} else {
/* Solve A * X = B using the factorization A = L*D*L', */
/* overwriting each right hand side vector with its solution. */
if (*nrhs <= 2) {
j = 1;
L80:
/* Solve L * x = b. */
i__1 = *n;
for (i__ = 2; i__ <= i__1; ++i__) {
i__2 = i__ + j * b_dim1;
i__3 = i__ + j * b_dim1;
i__4 = i__ - 1 + j * b_dim1;
i__5 = i__ - 1;
z__2.r = b[i__4].r * e[i__5].r - b[i__4].i * e[i__5].i,
z__2.i = b[i__4].r * e[i__5].i + b[i__4].i * e[i__5]
.r;
z__1.r = b[i__3].r - z__2.r, z__1.i = b[i__3].i - z__2.i;
b[i__2].r = z__1.r, b[i__2].i = z__1.i;
/* L90: */
}
/* Solve D * L' * x = b. */
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
i__2 = i__ + j * b_dim1;
i__3 = i__ + j * b_dim1;
i__4 = i__;
z__1.r = b[i__3].r / d__[i__4], z__1.i = b[i__3].i / d__[i__4]
;
b[i__2].r = z__1.r, b[i__2].i = z__1.i;
/* L100: */
}
for (i__ = *n - 1; i__ >= 1; --i__) {
i__1 = i__ + j * b_dim1;
i__2 = i__ + j * b_dim1;
i__3 = i__ + 1 + j * b_dim1;
d_cnjg(&z__3, &e[i__]);
z__2.r = b[i__3].r * z__3.r - b[i__3].i * z__3.i, z__2.i = b[
i__3].r * z__3.i + b[i__3].i * z__3.r;
z__1.r = b[i__2].r - z__2.r, z__1.i = b[i__2].i - z__2.i;
b[i__1].r = z__1.r, b[i__1].i = z__1.i;
/* L110: */
}
if (j < *nrhs) {
++j;
goto L80;
}
} else {
i__1 = *nrhs;
for (j = 1; j <= i__1; ++j) {
/* Solve L * x = b. */
i__2 = *n;
for (i__ = 2; i__ <= i__2; ++i__) {
i__3 = i__ + j * b_dim1;
i__4 = i__ + j * b_dim1;
i__5 = i__ - 1 + j * b_dim1;
i__6 = i__ - 1;
z__2.r = b[i__5].r * e[i__6].r - b[i__5].i * e[i__6].i,
z__2.i = b[i__5].r * e[i__6].i + b[i__5].i * e[
i__6].r;
z__1.r = b[i__4].r - z__2.r, z__1.i = b[i__4].i - z__2.i;
b[i__3].r = z__1.r, b[i__3].i = z__1.i;
/* L120: */
}
/* Solve D * L' * x = b. */
i__2 = *n + j * b_dim1;
i__3 = *n + j * b_dim1;
i__4 = *n;
z__1.r = b[i__3].r / d__[i__4], z__1.i = b[i__3].i / d__[i__4]
;
b[i__2].r = z__1.r, b[i__2].i = z__1.i;
for (i__ = *n - 1; i__ >= 1; --i__) {
i__2 = i__ + j * b_dim1;
i__3 = i__ + j * b_dim1;
i__4 = i__;
z__2.r = b[i__3].r / d__[i__4], z__2.i = b[i__3].i / d__[
i__4];
i__5 = i__ + 1 + j * b_dim1;
d_cnjg(&z__4, &e[i__]);
z__3.r = b[i__5].r * z__4.r - b[i__5].i * z__4.i, z__3.i =
b[i__5].r * z__4.i + b[i__5].i * z__4.r;
z__1.r = z__2.r - z__3.r, z__1.i = z__2.i - z__3.i;
b[i__2].r = z__1.r, b[i__2].i = z__1.i;
/* L130: */
}
/* L140: */
}
}
}
return 0;
/* End of ZPTTS2 */
} /* zptts2_ */
