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/*
-- MAGMA (version 2.9.0) --
Univ. of Tennessee, Knoxville
Univ. of California, Berkeley
Univ. of Colorado, Denver
@date January 2025
@generated from sparse/control/magma_zmslice.cpp, normal z -> s, Wed Jan 22 14:42:28 2025
@author Hartwig Anzt
*/
#include "magmasparse_internal.h"
#define THRESHOLD 10e-99
/**
Purpose
-------
Takes a matrix and extracts a slice for solving the system in parallel:
B = A( i:i+n, : ) and ALOC = A(i:i+n,i:i+n) and ANLOCA(0:start - end:n,:)
B is of size n x n, ALOC of size end-start x end-start,
ANLOC of size end-start x n
The last slice might be smaller. For the non-local parts, B is the identity.
comm contains 1ess in the locations that are non-local but needed to
solve local system.
Arguments
---------
@param[in]
num_slices magma_int_t
number of slices
@param[in]
slice magma_int_t
slice id (0.. num_slices-1)
@param[in]
A magma_s_matrix
sparse matrix in CSR
@param[out]
B magma_s_matrix*
sparse matrix in CSR
@param[out]
ALOC magma_s_matrix*
sparse matrix in CSR
@param[out]
ANLOC magma_s_matrix*
sparse matrix in CSR
@param[in,out]
comm_i magma_int_t*
communication plan
@param[in,out]
comm_v float*
communication plan
@param[in]
queue magma_queue_t
Queue to execute in.
@param[out]
start magma_int_t*
start of slice (row-index)
@param[out]
end magma_int_t*
end of slice (row-index)
@ingroup magmasparse_saux
********************************************************************/
extern "C" magma_int_t
magma_smslice(
magma_int_t num_slices,
magma_int_t slice,
magma_s_matrix A,
magma_s_matrix *B,
magma_s_matrix *ALOC,
magma_s_matrix *ANLOC,
magma_index_t *comm_i,
float *comm_v,
magma_int_t *start,
magma_int_t *end,
magma_queue_t queue )
{
magma_int_t info = 0;
// make sure the target structure is empty
magma_smfree( B, queue );
if( A.num_rows != A.num_cols ){
printf("%% error: only supported for square matrices.\n");
info = MAGMA_ERR_NOT_SUPPORTED;
goto cleanup;
}
if ( A.memory_location == Magma_CPU
&& A.storage_type == Magma_CSR ){
CHECK( magma_smconvert( A, B, Magma_CSR, Magma_CSR, queue ) );
magma_free_cpu( B->col );
magma_free_cpu( B->val );
CHECK( magma_smconvert( A, ALOC, Magma_CSR, Magma_CSR, queue ) );
magma_free_cpu( ALOC->col );
magma_free_cpu( ALOC->row );
magma_free_cpu( ALOC->val );
CHECK( magma_smconvert( A, ANLOC, Magma_CSR, Magma_CSR, queue ) );
magma_free_cpu( ANLOC->col );
magma_free_cpu( ANLOC->row );
magma_free_cpu( ANLOC->val );
magma_int_t i,j,k, nnz, nnz_loc=0, loc_row = 0, nnz_nloc = 0;
magma_index_t col;
magma_int_t size = magma_ceildiv( A.num_rows, num_slices );
magma_int_t lstart = slice*size;
magma_int_t lend = min( (slice+1)*size, A.num_rows );
// correct size for last slice
size = lend-lstart;
CHECK( magma_index_malloc_cpu( &ALOC->row, size+1 ) );
CHECK( magma_index_malloc_cpu( &ANLOC->row, size+1 ) );
// count elements for slice - identity for rest
nnz = A.row[ lend ] - A.row[ lstart ] + ( A.num_rows - size );
CHECK( magma_index_malloc_cpu( &B->col, nnz ) );
CHECK( magma_smalloc_cpu( &B->val, nnz ) );
// for the communication plan
for( i=0; i<A.num_rows; i++ ) {
comm_i[i] = 0;
comm_v[i] = MAGMA_S_ZERO;
}
k=0;
B->row[i] = 0;
ALOC->row[0] = 0;
ANLOC->row[0] = 0;
// identity above slice
for( i=0; i<lstart; i++ ) {
B->row[i+1] = B->row[i]+1;
B->val[k] = MAGMA_S_ONE;
B->col[k] = i;
k++;
}
// slice
for( i=lstart; i<lend; i++ ) {
B->row[i+1] = B->row[i] + (A.row[i+1]-A.row[i]);
for( j=A.row[i]; j<A.row[i+1]; j++ ){
B->val[k] = A.val[j];
col = A.col[j];
B->col[k] = col;
// communication plan
if( col<lstart || col>=lend ){
comm_i[ col ] = 1;
comm_v[ col ] = comm_v[ col ]
+ MAGMA_S_MAKE( MAGMA_S_ABS( A.val[j] ), 0.0 );
nnz_nloc++;
} else {
nnz_loc++;
}
k++;
}
loc_row++;
ALOC->row[ loc_row ] = nnz_loc;
ANLOC->row[ loc_row ] = nnz_nloc;
}
CHECK( magma_index_malloc_cpu( &ALOC->col, nnz_loc ) );
CHECK( magma_smalloc_cpu( &ALOC->val, nnz_loc ) );
ALOC->num_rows = size;
ALOC->num_cols = size;
ALOC->nnz = nnz_loc;
CHECK( magma_index_malloc_cpu( &ANLOC->col, nnz_nloc ) );
CHECK( magma_smalloc_cpu( &ANLOC->val, nnz_nloc ) );
ANLOC->num_rows = size;
ANLOC->num_cols = A.num_cols;
ANLOC->nnz = nnz_nloc;
nnz_loc = 0;
nnz_nloc = 0;
// local/nonlocal matrix
for( i=lstart; i<lend; i++ ) {
for( j=A.row[i]; j<A.row[i+1]; j++ ){
col = A.col[j];
// insert only in local part in ALOC, nonlocal in ANLOC
if( col<lstart || col>=lend ){
ANLOC->val[ nnz_nloc ] = A.val[j];
ANLOC->col[ nnz_nloc ] = col;
nnz_nloc++;
} else {
ALOC->val[ nnz_loc ] = A.val[j];
ALOC->col[ nnz_loc ] = col-lstart;
nnz_loc++;
}
}
}
// identity below slice
for( i=lend; i<A.num_rows; i++ ) {
B->row[i+1] = B->row[i]+1;
B->val[k] = MAGMA_S_ONE;
B->col[k] = i;
k++;
}
B->nnz = k;
*start = lstart;
*end = lend;
}
else {
printf("error: mslice only supported for CSR matrices on the CPU: %d %d.\n",
int(A.memory_location), int(A.storage_type) );
info = MAGMA_ERR_NOT_SUPPORTED;
}
cleanup:
return info;
}
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