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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/src/zbicgstab.cpp, normal z -> c, Wed Jan 22 14:42:34 2025
@author Hartwig Anzt
*/
#include "magmasparse_internal.h"
#define RTOLERANCE lapackf77_slamch( "E" )
#define ATOLERANCE lapackf77_slamch( "E" )
/**
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.
Arguments
---------
@param[in]
A magma_c_matrix
input matrix A
@param[in]
b magma_c_matrix
RHS b
@param[in,out]
x magma_c_matrix*
solution approximation
@param[in,out]
solver_par magma_c_solver_par*
solver parameters
@param[in]
queue magma_queue_t
Queue to execute in.
@ingroup magmasparse_cgesv
********************************************************************/
extern "C" magma_int_t
magma_cbicgstab(
magma_c_matrix A, magma_c_matrix b, magma_c_matrix *x,
magma_c_solver_par *solver_par,
magma_queue_t queue )
{
magma_int_t info = MAGMA_NOTCONVERGED;
// prepare solver feedback
solver_par->solver = Magma_BICGSTAB;
solver_par->numiter = 0;
solver_par->spmv_count = 0;
// some useful variables
magmaFloatComplex c_zero = MAGMA_C_ZERO;
magmaFloatComplex c_one = MAGMA_C_ONE;
magmaFloatComplex c_neg_one = MAGMA_C_NEG_ONE;
magma_int_t dofs = A.num_rows * b.num_cols;
// workspace
magma_c_matrix r={Magma_CSR}, rr={Magma_CSR}, p={Magma_CSR}, v={Magma_CSR}, s={Magma_CSR}, t={Magma_CSR};
CHECK( magma_cvinit( &r, Magma_DEV, A.num_rows, b.num_cols, c_zero, queue ));
CHECK( magma_cvinit( &rr,Magma_DEV, A.num_rows, b.num_cols, c_zero, queue ));
CHECK( magma_cvinit( &p, Magma_DEV, A.num_rows, b.num_cols, c_zero, queue ));
CHECK( magma_cvinit( &v, Magma_DEV, A.num_rows, b.num_cols, c_zero, queue ));
CHECK( magma_cvinit( &s, Magma_DEV, A.num_rows, b.num_cols, c_zero, queue ));
CHECK( magma_cvinit( &t, Magma_DEV, A.num_rows, b.num_cols, c_zero, queue ));
// solver variables
magmaFloatComplex alpha, beta, omega, rho_old, rho_new;
float betanom, nom0, r0, res, nomb;
//float den;
// solver setup
CHECK( magma_cresidualvec( A, b, *x, &r, &nom0, queue));
magma_ccopy( dofs, r.dval, 1, rr.dval, 1, queue ); // rr = r
betanom = nom0;
rho_new = magma_cdotc( dofs, r.dval, 1, r.dval, 1, queue ); // rho=<rr,r>
rho_old = omega = alpha = MAGMA_C_MAKE( 1.0, 0. );
solver_par->init_res = nom0;
CHECK( magma_c_spmv( c_one, A, r, c_zero, v, queue )); // z = A r
//den = MAGMA_C_REAL( magma_cdotc( dofs, v.dval, 1, r.dval, 1), queue ); // den = z' * r
nomb = magma_scnrm2( dofs, b.dval, 1, queue );
if ( nomb == 0.0 ){
nomb=1.0;
}
if ( (r0 = nomb * solver_par->rtol) < ATOLERANCE ){
r0 = ATOLERANCE;
}
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;
}
if ( nomb < r0 ) {
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++;
rho_new = magma_cdotc( dofs, rr.dval, 1, r.dval, 1, queue ); // rho=<rr,r>
beta = rho_new/rho_old * alpha/omega; // beta=rho/rho_old *alpha/omega
magma_cscal( dofs, beta, p.dval, 1, queue ); // p = beta*p
magma_caxpy( dofs, c_neg_one * omega * beta, v.dval, 1 , p.dval, 1, queue );
// p = p-omega*beta*v
magma_caxpy( dofs, c_one, r.dval, 1, p.dval, 1, queue ); // p = p+r
CHECK( magma_c_spmv( c_one, A, p, c_zero, v, queue )); // v = Ap
solver_par->spmv_count++;
alpha = rho_new / magma_cdotc( dofs, rr.dval, 1, v.dval, 1, queue );
magma_ccopy( dofs, r.dval, 1 , s.dval, 1, queue ); // s=r
magma_caxpy( dofs, c_neg_one * alpha, v.dval, 1 , s.dval, 1, queue ); // s=s-alpha*v
CHECK( magma_c_spmv( c_one, A, s, c_zero, t, queue )); // t=As
solver_par->spmv_count++;
omega = magma_cdotc( dofs, t.dval, 1, s.dval, 1, queue ) // omega = <s,t>/<t,t>
/ magma_cdotc( dofs, t.dval, 1, t.dval, 1, queue );
magma_caxpy( dofs, alpha, p.dval, 1 , x->dval, 1, queue ); // x=x+alpha*p
magma_caxpy( dofs, omega, s.dval, 1 , x->dval, 1, queue ); // x=x+omega*s
magma_ccopy( dofs, s.dval, 1 , r.dval, 1, queue ); // r=s
magma_caxpy( dofs, c_neg_one * omega, t.dval, 1 , r.dval, 1, queue ); // r=r-omega*t
res = betanom = magma_scnrm2( dofs, r.dval, 1, queue );
rho_old = rho_new; // rho_old=rho
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) res;
solver_par->timing[(solver_par->numiter)/solver_par->verbose]
= (real_Double_t) tempo2-tempo1;
}
}
if ( res/nomb <= solver_par->rtol || res <= solver_par->atol ){
break;
}
}
while ( solver_par->numiter+1 <= solver_par->maxiter );
tempo2 = magma_sync_wtime( queue );
solver_par->runtime = (real_Double_t) tempo2-tempo1;
float residual;
CHECK( magma_cresidualvec( A, b, *x, &r, &residual, queue));
solver_par->iter_res = res;
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->rtol*nomb ||
solver_par->iter_res < solver_par->atol ) {
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_cmfree(&r, queue );
magma_cmfree(&rr, queue );
magma_cmfree(&p, queue );
magma_cmfree(&v, queue );
magma_cmfree(&s, queue );
magma_cmfree(&t, queue );
solver_par->info = info;
return info;
} /* magma_cbicgstab */
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