#include "f2c.h"
#include "blaswrap.h"
/* Table of constant values */
static complex c_b1 = {0.f,0.f};
static complex c_b2 = {1.f,0.f};
static integer c__3 = 3;
static integer c__1 = 1;
/* Subroutine */ int clagsy_(integer *n, integer *k, real *d__, complex *a,
integer *lda, integer *iseed, complex *work, integer *info)
{
/* System generated locals */
integer a_dim1, a_offset, i__1, i__2, i__3, i__4, i__5, i__6, i__7, i__8,
i__9;
real r__1;
complex q__1, q__2, q__3, q__4;
/* Builtin functions */
double c_abs(complex *);
void c_div(complex *, complex *, complex *);
/* Local variables */
integer i__, j, ii, jj;
complex wa, wb;
real wn;
complex tau;
extern /* Subroutine */ int cgerc_(integer *, integer *, complex *,
complex *, integer *, complex *, integer *, complex *, integer *);
complex alpha;
extern /* Subroutine */ int cscal_(integer *, complex *, complex *,
integer *);
extern /* Complex */ VOID cdotc_(complex *, integer *, complex *, integer
*, complex *, integer *);
extern /* Subroutine */ int cgemv_(char *, integer *, integer *, complex *
, complex *, integer *, complex *, integer *, complex *, complex *
, integer *), caxpy_(integer *, complex *, complex *,
integer *, complex *, integer *), csymv_(char *, integer *,
complex *, complex *, integer *, complex *, integer *, complex *,
complex *, integer *);
extern doublereal scnrm2_(integer *, complex *, integer *);
extern /* Subroutine */ int clacgv_(integer *, complex *, integer *),
xerbla_(char *, integer *), clarnv_(integer *, integer *,
integer *, complex *);
/* -- LAPACK auxiliary test routine (version 3.1) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* CLAGSY generates a complex symmetric matrix A, by pre- and post- */
/* multiplying a real diagonal matrix D with a random unitary matrix: */
/* A = U*D*U**T. The semi-bandwidth may then be reduced to k by */
/* additional unitary transformations. */
/* Arguments */
/* ========= */
/* N (input) INTEGER */
/* The order of the matrix A. N >= 0. */
/* K (input) INTEGER */
/* The number of nonzero subdiagonals within the band of A. */
/* 0 <= K <= N-1. */
/* D (input) REAL array, dimension (N) */
/* The diagonal elements of the diagonal matrix D. */
/* A (output) COMPLEX array, dimension (LDA,N) */
/* The generated n by n symmetric matrix A (the full matrix is */
/* stored). */
/* LDA (input) INTEGER */
/* The leading dimension of the array A. LDA >= N. */
/* ISEED (input/output) INTEGER array, dimension (4) */
/* On entry, the seed of the random number generator; the array */
/* elements must be between 0 and 4095, and ISEED(4) must be */
/* odd. */
/* On exit, the seed is updated. */
/* WORK (workspace) COMPLEX array, dimension (2*N) */
/* INFO (output) INTEGER */
/* = 0: successful exit */
/* < 0: if INFO = -i, the i-th argument had an illegal value */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Test the input arguments */
/* Parameter adjustments */
--d__;
a_dim1 = *lda;
a_offset = 1 + a_dim1;
a -= a_offset;
--iseed;
--work;
/* Function Body */
*info = 0;
if (*n < 0) {
*info = -1;
} else if (*k < 0 || *k > *n - 1) {
*info = -2;
} else if (*lda < max(1,*n)) {
*info = -5;
}
if (*info < 0) {
i__1 = -(*info);
xerbla_("CLAGSY", &i__1);
return 0;
}
/* initialize lower triangle of A to diagonal matrix */
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
i__2 = *n;
for (i__ = j + 1; i__ <= i__2; ++i__) {
i__3 = i__ + j * a_dim1;
a[i__3].r = 0.f, a[i__3].i = 0.f;
/* L10: */
}
/* L20: */
}
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
i__2 = i__ + i__ * a_dim1;
i__3 = i__;
a[i__2].r = d__[i__3], a[i__2].i = 0.f;
/* L30: */
}
/* Generate lower triangle of symmetric matrix */
for (i__ = *n - 1; i__ >= 1; --i__) {
/* generate random reflection */
i__1 = *n - i__ + 1;
clarnv_(&c__3, &iseed[1], &i__1, &work[1]);
i__1 = *n - i__ + 1;
wn = scnrm2_(&i__1, &work[1], &c__1);
r__1 = wn / c_abs(&work[1]);
q__1.r = r__1 * work[1].r, q__1.i = r__1 * work[1].i;
wa.r = q__1.r, wa.i = q__1.i;
if (wn == 0.f) {
tau.r = 0.f, tau.i = 0.f;
} else {
q__1.r = work[1].r + wa.r, q__1.i = work[1].i + wa.i;
wb.r = q__1.r, wb.i = q__1.i;
i__1 = *n - i__;
c_div(&q__1, &c_b2, &wb);
cscal_(&i__1, &q__1, &work[2], &c__1);
work[1].r = 1.f, work[1].i = 0.f;
c_div(&q__1, &wb, &wa);
r__1 = q__1.r;
tau.r = r__1, tau.i = 0.f;
}
/* apply random reflection to A(i:n,i:n) from the left */
/* and the right */
/* compute y := tau * A * conjg(u) */
i__1 = *n - i__ + 1;
clacgv_(&i__1, &work[1], &c__1);
i__1 = *n - i__ + 1;
csymv_("Lower", &i__1, &tau, &a[i__ + i__ * a_dim1], lda, &work[1], &
c__1, &c_b1, &work[*n + 1], &c__1);
i__1 = *n - i__ + 1;
clacgv_(&i__1, &work[1], &c__1);
/* compute v := y - 1/2 * tau * ( u, y ) * u */
q__3.r = -.5f, q__3.i = -0.f;
q__2.r = q__3.r * tau.r - q__3.i * tau.i, q__2.i = q__3.r * tau.i +
q__3.i * tau.r;
i__1 = *n - i__ + 1;
cdotc_(&q__4, &i__1, &work[1], &c__1, &work[*n + 1], &c__1);
q__1.r = q__2.r * q__4.r - q__2.i * q__4.i, q__1.i = q__2.r * q__4.i
+ q__2.i * q__4.r;
alpha.r = q__1.r, alpha.i = q__1.i;
i__1 = *n - i__ + 1;
caxpy_(&i__1, &alpha, &work[1], &c__1, &work[*n + 1], &c__1);
/* apply the transformation as a rank-2 update to A(i:n,i:n) */
/* CALL CSYR2( 'Lower', N-I+1, -ONE, WORK, 1, WORK( N+1 ), 1, */
/* $ A( I, I ), LDA ) */
i__1 = *n;
for (jj = i__; jj <= i__1; ++jj) {
i__2 = *n;
for (ii = jj; ii <= i__2; ++ii) {
i__3 = ii + jj * a_dim1;
i__4 = ii + jj * a_dim1;
i__5 = ii - i__ + 1;
i__6 = *n + jj - i__ + 1;
q__3.r = work[i__5].r * work[i__6].r - work[i__5].i * work[
i__6].i, q__3.i = work[i__5].r * work[i__6].i + work[
i__5].i * work[i__6].r;
q__2.r = a[i__4].r - q__3.r, q__2.i = a[i__4].i - q__3.i;
i__7 = *n + ii - i__ + 1;
i__8 = jj - i__ + 1;
q__4.r = work[i__7].r * work[i__8].r - work[i__7].i * work[
i__8].i, q__4.i = work[i__7].r * work[i__8].i + work[
i__7].i * work[i__8].r;
q__1.r = q__2.r - q__4.r, q__1.i = q__2.i - q__4.i;
a[i__3].r = q__1.r, a[i__3].i = q__1.i;
/* L40: */
}
/* L50: */
}
/* L60: */
}
/* Reduce number of subdiagonals to K */
i__1 = *n - 1 - *k;
for (i__ = 1; i__ <= i__1; ++i__) {
/* generate reflection to annihilate A(k+i+1:n,i) */
i__2 = *n - *k - i__ + 1;
wn = scnrm2_(&i__2, &a[*k + i__ + i__ * a_dim1], &c__1);
r__1 = wn / c_abs(&a[*k + i__ + i__ * a_dim1]);
i__2 = *k + i__ + i__ * a_dim1;
q__1.r = r__1 * a[i__2].r, q__1.i = r__1 * a[i__2].i;
wa.r = q__1.r, wa.i = q__1.i;
if (wn == 0.f) {
tau.r = 0.f, tau.i = 0.f;
} else {
i__2 = *k + i__ + i__ * a_dim1;
q__1.r = a[i__2].r + wa.r, q__1.i = a[i__2].i + wa.i;
wb.r = q__1.r, wb.i = q__1.i;
i__2 = *n - *k - i__;
c_div(&q__1, &c_b2, &wb);
cscal_(&i__2, &q__1, &a[*k + i__ + 1 + i__ * a_dim1], &c__1);
i__2 = *k + i__ + i__ * a_dim1;
a[i__2].r = 1.f, a[i__2].i = 0.f;
c_div(&q__1, &wb, &wa);
r__1 = q__1.r;
tau.r = r__1, tau.i = 0.f;
}
/* apply reflection to A(k+i:n,i+1:k+i-1) from the left */
i__2 = *n - *k - i__ + 1;
i__3 = *k - 1;
cgemv_("Conjugate transpose", &i__2, &i__3, &c_b2, &a[*k + i__ + (i__
+ 1) * a_dim1], lda, &a[*k + i__ + i__ * a_dim1], &c__1, &
c_b1, &work[1], &c__1);
i__2 = *n - *k - i__ + 1;
i__3 = *k - 1;
q__1.r = -tau.r, q__1.i = -tau.i;
cgerc_(&i__2, &i__3, &q__1, &a[*k + i__ + i__ * a_dim1], &c__1, &work[
1], &c__1, &a[*k + i__ + (i__ + 1) * a_dim1], lda);
/* apply reflection to A(k+i:n,k+i:n) from the left and the right */
/* compute y := tau * A * conjg(u) */
i__2 = *n - *k - i__ + 1;
clacgv_(&i__2, &a[*k + i__ + i__ * a_dim1], &c__1);
i__2 = *n - *k - i__ + 1;
csymv_("Lower", &i__2, &tau, &a[*k + i__ + (*k + i__) * a_dim1], lda,
&a[*k + i__ + i__ * a_dim1], &c__1, &c_b1, &work[1], &c__1);
i__2 = *n - *k - i__ + 1;
clacgv_(&i__2, &a[*k + i__ + i__ * a_dim1], &c__1);
/* compute v := y - 1/2 * tau * ( u, y ) * u */
q__3.r = -.5f, q__3.i = -0.f;
q__2.r = q__3.r * tau.r - q__3.i * tau.i, q__2.i = q__3.r * tau.i +
q__3.i * tau.r;
i__2 = *n - *k - i__ + 1;
cdotc_(&q__4, &i__2, &a[*k + i__ + i__ * a_dim1], &c__1, &work[1], &
c__1);
q__1.r = q__2.r * q__4.r - q__2.i * q__4.i, q__1.i = q__2.r * q__4.i
+ q__2.i * q__4.r;
alpha.r = q__1.r, alpha.i = q__1.i;
i__2 = *n - *k - i__ + 1;
caxpy_(&i__2, &alpha, &a[*k + i__ + i__ * a_dim1], &c__1, &work[1], &
c__1);
/* apply symmetric rank-2 update to A(k+i:n,k+i:n) */
/* CALL CSYR2( 'Lower', N-K-I+1, -ONE, A( K+I, I ), 1, WORK, 1, */
/* $ A( K+I, K+I ), LDA ) */
i__2 = *n;
for (jj = *k + i__; jj <= i__2; ++jj) {
i__3 = *n;
for (ii = jj; ii <= i__3; ++ii) {
i__4 = ii + jj * a_dim1;
i__5 = ii + jj * a_dim1;
i__6 = ii + i__ * a_dim1;
i__7 = jj - *k - i__ + 1;
q__3.r = a[i__6].r * work[i__7].r - a[i__6].i * work[i__7].i,
q__3.i = a[i__6].r * work[i__7].i + a[i__6].i * work[
i__7].r;
q__2.r = a[i__5].r - q__3.r, q__2.i = a[i__5].i - q__3.i;
i__8 = ii - *k - i__ + 1;
i__9 = jj + i__ * a_dim1;
q__4.r = work[i__8].r * a[i__9].r - work[i__8].i * a[i__9].i,
q__4.i = work[i__8].r * a[i__9].i + work[i__8].i * a[
i__9].r;
q__1.r = q__2.r - q__4.r, q__1.i = q__2.i - q__4.i;
a[i__4].r = q__1.r, a[i__4].i = q__1.i;
/* L70: */
}
/* L80: */
}
i__2 = *k + i__ + i__ * a_dim1;
q__1.r = -wa.r, q__1.i = -wa.i;
a[i__2].r = q__1.r, a[i__2].i = q__1.i;
i__2 = *n;
for (j = *k + i__ + 1; j <= i__2; ++j) {
i__3 = j + i__ * a_dim1;
a[i__3].r = 0.f, a[i__3].i = 0.f;
/* L90: */
}
/* L100: */
}
/* Store full symmetric matrix */
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
i__2 = *n;
for (i__ = j + 1; i__ <= i__2; ++i__) {
i__3 = j + i__ * a_dim1;
i__4 = i__ + j * a_dim1;
a[i__3].r = a[i__4].r, a[i__3].i = a[i__4].i;
/* L110: */
}
/* L120: */
}
return 0;
/* End of CLAGSY */
} /* clagsy_ */