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/*
-- MAGMA (version 2.9.0) --
Univ. of Tennessee, Knoxville
Univ. of California, Berkeley
Univ. of Colorado, Denver
@date January 2025
@precisions normal z -> s d c
@author Hartwig Anzt
*/
#include "magmasparse_internal.h"
#define RTOLERANCE lapackf77_dlamch( "E" )
#define ATOLERANCE lapackf77_dlamch( "E" )
#define q(i) (q.dval + (i)*dofs)
/**
Purpose
-------
Solves a system of linear equations
A * X = B
where A is a general matrix.
This is a GPU implementation of the Biconjugate Gradient Stabilized method.
The difference to magma_zbicgstab is that we use specifically designed
kernels merging multiple operations into one kernel.
Arguments
---------
@param[in]
A magma_z_matrix
input matrix A
@param[in]
b magma_z_matrix
RHS b
@param[in,out]
x magma_z_matrix*
solution approximation
@param[in,out]
solver_par magma_z_solver_par*
solver parameters
@param[in]
queue magma_queue_t
Queue to execute in.
@ingroup magmasparse_zgesv
********************************************************************/
extern "C" magma_int_t
magma_zbicgstab_merge3(
magma_z_matrix A, magma_z_matrix b,
magma_z_matrix *x, magma_z_solver_par *solver_par,
magma_queue_t queue )
{
magma_int_t info = MAGMA_NOTCONVERGED;
// prepare solver feedback
solver_par->solver = Magma_BICGSTABMERGE;
solver_par->numiter = 0;
solver_par->spmv_count = 0;
// solver variables
magmaDoubleComplex alpha, beta, omega, rho_old, rho_new, *skp_h={0};
double nom, nom0, betanom, nomb;
// some useful variables
magmaDoubleComplex c_zero = MAGMA_Z_ZERO, c_one = MAGMA_Z_ONE;
magma_int_t dofs = A.num_rows;
// workspace
magma_z_matrix q={Magma_CSR}, r={Magma_CSR}, rr={Magma_CSR}, p={Magma_CSR}, v={Magma_CSR}, s={Magma_CSR}, t={Magma_CSR};
magmaDoubleComplex *d1=NULL, *d2=NULL, *skp=NULL;
d1 = NULL;
d2 = NULL;
skp = NULL;
CHECK( magma_zmalloc( &d1, dofs*(2) ));
CHECK( magma_zmalloc( &d2, dofs*(2) ));
// array for the parameters
CHECK( magma_zmalloc( &skp, 8 ));
// skp = [alpha|beta|omega|rho_old|rho|nom|tmp1|tmp2]
CHECK( magma_zvinit( &q, Magma_DEV, dofs*6, 1, c_zero, queue ));
// q = rr|r|p|v|s|t
rr.memory_location = Magma_DEV; rr.dval = NULL; rr.num_rows = rr.nnz = dofs; rr.num_cols = 1; rr.storage_type = Magma_DENSE;
r.memory_location = Magma_DEV; r.dval = NULL; r.num_rows = r.nnz = dofs; r.num_cols = 1; r.storage_type = Magma_DENSE;
p.memory_location = Magma_DEV; p.dval = NULL; p.num_rows = p.nnz = dofs; p.num_cols = 1; p.storage_type = Magma_DENSE;
v.memory_location = Magma_DEV; v.dval = NULL; v.num_rows = v.nnz = dofs; v.num_cols = 1; v.storage_type = Magma_DENSE;
s.memory_location = Magma_DEV; s.dval = NULL; s.num_rows = s.nnz = dofs; s.num_cols = 1; s.storage_type = Magma_DENSE;
t.memory_location = Magma_DEV; t.dval = NULL; t.num_rows = t.nnz = dofs; t.num_cols = 1; t.storage_type = Magma_DENSE;
rr.dval = q(0);
r.dval = q(1);
p.dval = q(2);
v.dval = q(3);
s.dval = q(4);
t.dval = q(5);
// solver setup
CHECK( magma_zresidualvec( A, b, *x, &r, &nom0, queue));
magma_zcopy( dofs, r.dval, 1, q(0), 1, queue ); // rr = r
magma_zcopy( dofs, r.dval, 1, q(1), 1, queue ); // q = r
betanom = nom0;
nom = nom0*nom0;
rho_new = magma_zdotc( dofs, r.dval, 1, r.dval, 1, queue ); // rho=<rr,r>
rho_old = omega = alpha = MAGMA_Z_MAKE( 1.0, 0. );
beta = rho_new;
solver_par->init_res = nom0;
// array on host for the parameters
CHECK( magma_zmalloc_cpu( &skp_h, 8 ));
nomb = magma_dznrm2( dofs, b.dval, 1, queue );
if ( nomb == 0.0 ){
nomb=1.0;
}
solver_par->final_res = solver_par->init_res;
solver_par->iter_res = solver_par->init_res;
if ( solver_par->verbose > 0 ) {
solver_par->res_vec[0] = nom0;
solver_par->timing[0] = 0.0;
}
skp_h[0]=alpha;
skp_h[1]=beta;
skp_h[2]=omega;
skp_h[3]=rho_old;
skp_h[4]=rho_new;
skp_h[5]=MAGMA_Z_MAKE(nom, 0.0);
magma_zsetvector( 8, skp_h, 1, skp, 1, queue );
CHECK( magma_z_spmv( c_one, A, r, c_zero, v, queue )); // z = A r
nomb = magma_dznrm2( dofs, b.dval, 1, queue );
if( nom0 < solver_par->atol ||
nom0/nomb < solver_par->rtol ){
info = MAGMA_SUCCESS;
goto cleanup;
}
//Chronometry
real_Double_t tempo1, tempo2;
tempo1 = magma_sync_wtime( queue );
solver_par->numiter = 0;
solver_par->spmv_count = 0;
// start iteration
do
{
solver_par->numiter++;
// computes p=r+beta*(p-omega*v)
CHECK( magma_zbicgmerge1( dofs, skp, v.dval, r.dval, p.dval, queue ));
CHECK( magma_z_spmv( c_one, A, p, c_zero, v, queue )); // v = Ap
solver_par->spmv_count++;
CHECK( magma_zmdotc( dofs, 1, q.dval, v.dval, d1, d2, skp, queue ));
CHECK( magma_zbicgmerge4( 1, skp, queue ));
CHECK( magma_zbicgmerge2( dofs, skp, r.dval, v.dval, s.dval, queue )); // s=r-alpha*v
CHECK( magma_z_spmv( c_one, A, s, c_zero, t, queue )); // t=As
solver_par->spmv_count++;
CHECK( magma_zmdotc( dofs, 2, q.dval+4*dofs, t.dval, d1, d2, skp+6, queue ));
CHECK( magma_zbicgmerge4( 2, skp, queue ));
CHECK( magma_zbicgmerge_xrbeta( dofs, d1, d2, q.dval, r.dval, p.dval,
s.dval, t.dval, x->dval, skp, queue ));
// check stopping criterion
magma_zgetvector_async( 1 , skp+5, 1, skp_h+5, 1, queue );
betanom = sqrt(MAGMA_Z_REAL(skp_h[5]));
if ( solver_par->verbose > 0 ) {
tempo2 = magma_sync_wtime( queue );
if ( (solver_par->numiter)%solver_par->verbose==0 ) {
solver_par->res_vec[(solver_par->numiter)/solver_par->verbose]
= (real_Double_t) betanom;
solver_par->timing[(solver_par->numiter)/solver_par->verbose]
= (real_Double_t) tempo2-tempo1;
}
}
if ( betanom < solver_par->atol ||
betanom/nomb < solver_par->rtol ) {
break;
}
}
while ( solver_par->numiter+1 <= solver_par->maxiter );
tempo2 = magma_sync_wtime( queue );
solver_par->runtime = (real_Double_t) tempo2-tempo1;
double residual;
CHECK( magma_zresidualvec( A, b, *x, &r, &residual, queue));
solver_par->iter_res = betanom;
solver_par->final_res = residual;
if ( solver_par->numiter < solver_par->maxiter ) {
info = MAGMA_SUCCESS;
} else if ( solver_par->init_res > solver_par->final_res ) {
if ( solver_par->verbose > 0 ) {
if ( (solver_par->numiter)%solver_par->verbose==0 ) {
solver_par->res_vec[(solver_par->numiter)/solver_par->verbose]
= (real_Double_t) betanom;
solver_par->timing[(solver_par->numiter)/solver_par->verbose]
= (real_Double_t) tempo2-tempo1;
}
}
info = MAGMA_SLOW_CONVERGENCE;
if( solver_par->iter_res < solver_par->atol ||
solver_par->iter_res/solver_par->init_res < solver_par->rtol ){
info = MAGMA_SUCCESS;
}
}
else {
if ( solver_par->verbose > 0 ) {
if ( (solver_par->numiter)%solver_par->verbose==0 ) {
solver_par->res_vec[(solver_par->numiter)/solver_par->verbose]
= (real_Double_t) betanom;
solver_par->timing[(solver_par->numiter)/solver_par->verbose]
= (real_Double_t) tempo2-tempo1;
}
}
info = MAGMA_DIVERGENCE;
}
cleanup:
magma_zmfree(&q, queue ); // frees all vectors
magma_free(d1);
magma_free(d2);
magma_free( skp );
magma_free_cpu( skp_h );
solver_par->info = info;
return info;
} /* zbicgstab_merge */
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