extern "C" magma_int_t
magma_slaex0(magma_int_t n, float* d, float* e, float* q, magma_int_t ldq,
float* work, magma_int_t* iwork, magmaFloat_ptr dwork,
magma_vec_t range, float vl, float vu,
magma_int_t il, magma_int_t iu, magma_int_t* info, magma_queue_t queue)
{
/*
-- MAGMA (version 1.1.0) --
Univ. of Tennessee, Knoxville
Univ. of California, Berkeley
Univ. of Colorado, Denver
@date January 2014
.. Scalar Arguments ..
CHARACTER RANGE
INTEGER IL, IU, INFO, LDQ, N
REAL VL, VU
..
.. Array Arguments ..
INTEGER IWORK( * )
REAL D( * ), E( * ), Q( LDQ, * ),
$ WORK( * ), DWORK( * )
..
Purpose
=======
SLAEX0 computes all eigenvalues and the choosen eigenvectors of a
symmetric tridiagonal matrix using the divide and conquer method.
Arguments
=========
N (input) INTEGER
The dimension of the symmetric tridiagonal matrix. N >= 0.
D (input/output) REAL array, dimension (N)
On entry, the main diagonal of the tridiagonal matrix.
On exit, its eigenvalues.
E (input) REAL array, dimension (N-1)
The off-diagonal elements of the tridiagonal matrix.
On exit, E has been destroyed.
Q (input/output) REAL array, dimension (LDQ, N)
On entry, Q will be the identity matrix.
On exit, Q contains the eigenvectors of the
tridiagonal matrix.
LDQ (input) INTEGER
The leading dimension of the array Q. If eigenvectors are
desired, then LDQ >= max(1,N). In any case, LDQ >= 1.
WORK (workspace) REAL array,
the dimension of WORK must be at least 4*N + N**2.
IWORK (workspace) INTEGER array,
the dimension of IWORK must be at least 3 + 5*N.
DWORK (device workspace) REAL array, dimension (3*N*N/2+3*N)
RANGE (input) CHARACTER*1
= 'A': all eigenvalues will be found.
= 'V': all eigenvalues in the half-open interval (VL,VU]
will be found.
= 'I': the IL-th through IU-th eigenvalues will be found.
VL (input) REAL
VU (input) REAL
If RANGE='V', the lower and upper bounds of the interval to
be searched for eigenvalues. VL < VU.
Not referenced if RANGE = 'A' or 'I'.
IL (input) INTEGER
IU (input) INTEGER
If RANGE='I', the indices (in ascending order) of the
smallest and largest eigenvalues to be returned.
1 <= IL <= IU <= N, if N > 0; IL = 1 and IU = 0 if N = 0.
Not referenced if RANGE = 'A' or 'V'.
INFO (output) INTEGER
= 0: successful exit.
< 0: if INFO = -i, the i-th argument had an illegal value.
> 0: The algorithm failed to compute an eigenvalue while
working on the submatrix lying in rows and columns
INFO/(N+1) through mod(INFO,N+1).
Further Details
===============
Based on contributions by
Jeff Rutter, Computer Science Division, University of California
at Berkeley, USA
=====================================================================
*/
magma_int_t ione = 1;
magma_vec_t range_ = range;
magma_int_t curlvl, curprb, i, indxq;
magma_int_t j, k, matsiz, msd2, smlsiz;
magma_int_t submat, subpbs, tlvls;
// Test the input parameters.
*info = 0;
if( n < 0 )
*info = -1;
else if( ldq < max(1, n) )
*info = -5;
if( *info != 0 ){
magma_xerbla( __func__, -*info );
return MAGMA_ERR_ILLEGAL_VALUE;
}
// Quick return if possible
if(n == 0)
return MAGMA_SUCCESS;
smlsiz = get_slaex0_smlsize();
// Determine the size and placement of the submatrices, and save in
// the leading elements of IWORK.
iwork[0] = n;
subpbs= 1;
tlvls = 0;
while (iwork[subpbs - 1] > smlsiz) {
for (j = subpbs; j > 0; --j){
iwork[2*j - 1] = (iwork[j-1]+1)/2;
iwork[2*j - 2] = iwork[j-1]/2;
}
++tlvls;
subpbs *= 2;
}
for (j=1; j<subpbs; ++j)
iwork[j] += iwork[j-1];
// Divide the matrix into SUBPBS submatrices of size at most SMLSIZ+1
// using rank-1 modifications (cuts).
for(i=0; i < subpbs-1; ++i){
submat = iwork[i];
d[submat-1] -= MAGMA_S_ABS(e[submat-1]);
d[submat] -= MAGMA_S_ABS(e[submat-1]);
}
indxq = 4*n + 3;
// Solve each submatrix eigenproblem at the bottom of the divide and
// conquer tree.
char char_I[] = {'I', 0};
//#define ENABLE_TIMER
#ifdef ENABLE_TIMER
magma_timestr_t start, end;
start = get_current_time();
#endif
for (i = 0; i < subpbs; ++i){
if(i == 0){
submat = 0;
matsiz = iwork[0];
} else {
submat = iwork[i-1];
matsiz = iwork[i] - iwork[i-1];
}
lapackf77_ssteqr(char_I , &matsiz, &d[submat], &e[submat],
Q(submat, submat), &ldq, work, info); // change to edc?
if(*info != 0){
printf("info: %d\n, submat: %d\n", (int) *info, (int) submat);
*info = (submat+1)*(n+1) + submat + matsiz;
printf("info: %d\n", (int) *info);
return MAGMA_SUCCESS;
}
k = 1;
for(j = submat; j < iwork[i]; ++j){
iwork[indxq+j] = k;
++k;
}
}
#ifdef ENABLE_TIMER
end = get_current_time();
printf("for: ssteqr = %6.2f\n", GetTimerValue(start,end)/1000.);
#endif
// Successively merge eigensystems of adjacent submatrices
// into eigensystem for the corresponding larger matrix.
curlvl = 1;
while (subpbs > 1){
#ifdef ENABLE_TIMER
magma_timestr_t start, end;
start = get_current_time();
#endif
for (i=0; i<subpbs-1; i+=2){
if(i == 0){
submat = 0;
matsiz = iwork[1];
msd2 = iwork[0];
} else {
submat = iwork[i-1];
matsiz = iwork[i+1] - iwork[i-1];
msd2 = matsiz / 2;
}
// Merge lower order eigensystems (of size MSD2 and MATSIZ - MSD2)
// into an eigensystem of size MATSIZ.
// SLAEX1 is used only for the full eigensystem of a tridiagonal
// matrix.
if (matsiz == n)
range_=range;
else
// We need all the eigenvectors if it is not last step
range_= MagmaAllVec;
magma_slaex1(matsiz, &d[submat], Q(submat, submat), ldq,
&iwork[indxq+submat], e[submat+msd2-1], msd2,
work, &iwork[subpbs], dwork,
range_, vl, vu, il, iu, info, queue);
if(*info != 0){
*info = (submat+1)*(n+1) + submat + matsiz;
return MAGMA_SUCCESS;
}
iwork[i/2]= iwork[i+1];
}
subpbs /= 2;
++curlvl;
#ifdef ENABLE_TIMER
end = get_current_time();
printf("%d: time: %6.2f\n", curlvl, GetTimerValue(start,end)/1000.);
#endif
}
// Re-merge the eigenvalues/vectors which were deflated at the final
// merge step.
for(i = 0; i<n; ++i){
j = iwork[indxq+i] - 1;
work[i] = d[j];
blasf77_scopy(&n, Q(0, j), &ione, &work[ n*(i+1) ], &ione);
}
blasf77_scopy(&n, work, &ione, d, &ione);
char char_A[] = {'A',0};
lapackf77_slacpy ( char_A, &n, &n, &work[n], &n, q, &ldq );
return MAGMA_SUCCESS;
} /* magma_slaex0 */
/**
Purpose
-------
SLAEX0 computes all eigenvalues and the choosen eigenvectors of a
symmetric tridiagonal matrix using the divide and conquer method.
Arguments
---------
@param[in]
n INTEGER
The dimension of the symmetric tridiagonal matrix. N >= 0.
@param[in,out]
d REAL array, dimension (N)
On entry, the main diagonal of the tridiagonal matrix.
On exit, its eigenvalues.
@param[in]
e REAL array, dimension (N-1)
The off-diagonal elements of the tridiagonal matrix.
On exit, E has been destroyed.
@param[in,out]
Q REAL array, dimension (LDQ, N)
On entry, Q will be the identity matrix.
On exit, Q contains the eigenvectors of the
tridiagonal matrix.
@param[in]
ldq INTEGER
The leading dimension of the array Q. If eigenvectors are
desired, then LDQ >= max(1,N). In any case, LDQ >= 1.
@param
work (workspace) REAL array,
the dimension of WORK >= 4*N + N**2.
@param
iwork (workspace) INTEGER array,
the dimension of IWORK >= 3 + 5*N.
@param
dwork (workspace) REAL array, dimension (3*N*N/2+3*N)
@param[in]
range magma_range_t
- = MagmaRangeAll: all eigenvalues will be found.
- = MagmaRangeV: all eigenvalues in the half-open interval (VL,VU]
will be found.
- = MagmaRangeI: the IL-th through IU-th eigenvalues will be found.
@param[in]
vl REAL
@param[in]
vu REAL
If RANGE=MagmaRangeV, the lower and upper bounds of the interval to
be searched for eigenvalues. VL < VU.
Not referenced if RANGE = MagmaRangeAll or MagmaRangeI.
@param[in]
il INTEGER
@param[in]
iu INTEGER
If RANGE=MagmaRangeI, the indices (in ascending order) of the
smallest and largest eigenvalues to be returned.
1 <= IL <= IU <= N, if N > 0; IL = 1 and IU = 0 if N = 0.
Not referenced if RANGE = MagmaRangeAll or MagmaRangeV.
@param[out]
info INTEGER
- = 0: successful exit.
- < 0: if INFO = -i, the i-th argument had an illegal value.
- > 0: The algorithm failed to compute an eigenvalue while
working on the submatrix lying in rows and columns
INFO/(N+1) through mod(INFO,N+1).
Further Details
---------------
Based on contributions by
Jeff Rutter, Computer Science Division, University of California
at Berkeley, USA
@ingroup magma_ssyev_aux
********************************************************************/
extern "C" magma_int_t
magma_slaex0(
magma_int_t n,
float *d, float *e,
float *Q, magma_int_t ldq,
float *work, magma_int_t *iwork,
magmaFloat_ptr dwork,
magma_range_t range, float vl, float vu,
magma_int_t il, magma_int_t iu,
magma_int_t *info)
{
#define Q(i_,j_) (Q + (i_) + (j_)*ldq)
magma_int_t ione = 1;
magma_range_t range2;
magma_int_t curlvl, i, indxq;
magma_int_t j, k, matsiz, msd2, smlsiz;
magma_int_t submat, subpbs, tlvls;
// Test the input parameters.
*info = 0;
if ( n < 0 )
*info = -1;
else if ( ldq < max(1, n) )
*info = -5;
if ( *info != 0 ) {
magma_xerbla( __func__, -(*info) );
return *info;
}
// Quick return if possible
if (n == 0)
return *info;
smlsiz = magma_get_smlsize_divideconquer();
// Determine the size and placement of the submatrices, and save in
// the leading elements of IWORK.
iwork[0] = n;
subpbs= 1;
tlvls = 0;
while (iwork[subpbs - 1] > smlsiz) {
for (j = subpbs; j > 0; --j) {
iwork[2*j - 1] = (iwork[j-1]+1)/2;
iwork[2*j - 2] = iwork[j-1]/2;
}
++tlvls;
subpbs *= 2;
}
for (j=1; j < subpbs; ++j)
iwork[j] += iwork[j-1];
// Divide the matrix into SUBPBS submatrices of size at most SMLSIZ+1
// using rank-1 modifications (cuts).
for (i=0; i < subpbs-1; ++i) {
submat = iwork[i];
d[submat-1] -= MAGMA_S_ABS(e[submat-1]);
d[submat] -= MAGMA_S_ABS(e[submat-1]);
}
indxq = 4*n + 3;
// Solve each submatrix eigenproblem at the bottom of the divide and
// conquer tree.
magma_timer_t time=0;
timer_start( time );
for (i = 0; i < subpbs; ++i) {
if (i == 0) {
submat = 0;
matsiz = iwork[0];
} else {
submat = iwork[i-1];
matsiz = iwork[i] - iwork[i-1];
}
lapackf77_ssteqr("I", &matsiz, &d[submat], &e[submat],
Q(submat, submat), &ldq, work, info); // change to edc?
if (*info != 0) {
printf("info: %d\n, submat: %d\n", (int) *info, (int) submat);
*info = (submat+1)*(n+1) + submat + matsiz;
printf("info: %d\n", (int) *info);
return *info;
}
k = 1;
for (j = submat; j < iwork[i]; ++j) {
iwork[indxq+j] = k;
++k;
}
}
timer_stop( time );
timer_printf( " for: ssteqr = %6.2f\n", time );
// Successively merge eigensystems of adjacent submatrices
// into eigensystem for the corresponding larger matrix.
curlvl = 1;
while (subpbs > 1) {
timer_start( time );
for (i=0; i < subpbs-1; i += 2) {
if (i == 0) {
submat = 0;
matsiz = iwork[1];
msd2 = iwork[0];
} else {
submat = iwork[i-1];
matsiz = iwork[i+1] - iwork[i-1];
msd2 = matsiz / 2;
}
// Merge lower order eigensystems (of size MSD2 and MATSIZ - MSD2)
// into an eigensystem of size MATSIZ.
// SLAEX1 is used only for the full eigensystem of a tridiagonal
// matrix.
if (matsiz == n)
range2 = range;
else
// We need all the eigenvectors if it is not last step
range2 = MagmaRangeAll;
magma_slaex1(matsiz, &d[submat], Q(submat, submat), ldq,
&iwork[indxq+submat], e[submat+msd2-1], msd2,
work, &iwork[subpbs], dwork,
range2, vl, vu, il, iu, info);
if (*info != 0) {
*info = (submat+1)*(n+1) + submat + matsiz;
return *info;
}
iwork[i/2]= iwork[i+1];
}
subpbs /= 2;
++curlvl;
timer_stop( time );
timer_printf("%d: time: %6.2f\n", (int) curlvl, time );
}
// Re-merge the eigenvalues/vectors which were deflated at the final
// merge step.
for (i = 0; i < n; ++i) {
j = iwork[indxq+i] - 1;
work[i] = d[j];
blasf77_scopy(&n, Q(0, j), &ione, &work[ n*(i+1) ], &ione);
}
blasf77_scopy(&n, work, &ione, d, &ione);
lapackf77_slacpy( "A", &n, &n, &work[n], &n, Q, &ldq );
return *info;
} /* magma_slaex0 */
