/* k output , l input */
int bicg(spinor * const k, spinor * const l, double eps_sq, const int rel_prec) {
double err, d1, squarenorm=0.;
complex rho0, rho1, omega, alpha, beta, nom, denom;
int iteration, N=VOLUME/2;
spinor * r, * p, * v, *hatr, * s, * t, * P, * Q;
if(ITER_MAX_BCG > 0) {
hatr = g_spinor_field[DUM_SOLVER];
r = g_spinor_field[DUM_SOLVER+1];
v = g_spinor_field[DUM_SOLVER+2];
p = g_spinor_field[DUM_SOLVER+3];
s = g_spinor_field[DUM_SOLVER+4];
t = g_spinor_field[DUM_SOLVER+5];
P = k;
Q = l;
squarenorm = square_norm(Q, VOLUME/2, 1);
Mtm_plus_psi(r, P);
gamma5(g_spinor_field[DUM_SOLVER], l, VOLUME/2);
diff(p, hatr, r, N);
assign(r, p, N);
assign(hatr, p, N);
rho0 = scalar_prod(hatr, r, N, 1);
for(iteration = 0; iteration < ITER_MAX_BCG; iteration++){
err = square_norm(r, N, 1);
if(g_proc_id == g_stdio_proc && g_debug_level > 1) {
printf("BiCGstab: iterations: %d res^2 %e\n", iteration, err);
fflush(stdout);
}
if (((err <= eps_sq) && (rel_prec == 0))
|| ((err <= eps_sq*squarenorm) && (rel_prec == 1))){
break;
}
Mtm_plus_psi(v, p);
denom = scalar_prod(hatr, v, N, 1);
_div_complex(alpha, rho0, denom);
assign(s, r, N);
assign_diff_mul(s, v, alpha, N);
Mtm_plus_psi(t, s);
omega = scalar_prod(t,s, N, 1);
d1 = square_norm(t, N, 1);
omega.re/=d1; omega.im/=d1;
assign_add_mul_add_mul(P, p, s, alpha, omega, N);
assign(r, s, N);
assign_diff_mul(r, t, omega, N);
rho1 = scalar_prod(hatr, r, N, 1);
_mult_assign_complex(nom, alpha, rho1);
_mult_assign_complex(denom, omega, rho0);
_div_complex(beta, nom, denom);
omega.re=-omega.re; omega.im=-omega.im;
assign_mul_bra_add_mul_ket_add(p, v, r, omega, beta, N);
rho0.re = rho1.re; rho0.im = rho1.im;
}
if(g_proc_id==0 && g_debug_level > 0) {
printf("BiCGstab: iterations: %d eps_sq: %1.4e\n", iteration, eps_sq);
}
}
else{
iteration = ITER_MAX_BCG;
gamma5(k, l, VOLUME/2);
}
/* if bicg fails, redo with conjugate gradient */
if(iteration>=ITER_MAX_BCG){
iteration = solve_cg(k,l,eps_sq, rel_prec);
/* Save the solution for reuse! not needed since Chronological inverter is there */
/* assign(g_spinor_field[DUM_DERI+6], k, VOLUME/2); */
Qtm_minus_psi(k, k);;
}
return iteration;
}
/* P inout (guess for the solving spinor)
Q input
*/
int bicgstab_complex(spinor * const P,spinor * const Q, const int max_iter,
double eps_sq, const int rel_prec,
const int N, matrix_mult f){
double err, d1, squarenorm;
complex rho0, rho1, omega, alpha, beta, nom, denom;
int i;
spinor * r, * p, * v, *hatr, * s, * t;
spinor ** solver_field = NULL;
const int nr_sf = 6;
if(N == VOLUME) {
init_solver_field(&solver_field, VOLUMEPLUSRAND, nr_sf);
}
else {
init_solver_field(&solver_field, VOLUMEPLUSRAND/2, nr_sf);
}
hatr = solver_field[0];
r = solver_field[1];
v = solver_field[2];
p = solver_field[3];
s = solver_field[4];
t = solver_field[5];
f(r, P);
diff(p, Q, r, N);
assign(r, p, N);
assign(hatr, p, N);
rho0 = scalar_prod(hatr, r, N, 1);
squarenorm = square_norm(Q, N, 1);
for(i = 0; i < max_iter; i++){
err = square_norm(r, N, 1);
if(g_proc_id == g_stdio_proc && g_debug_level > 1) {
printf("%d %e\n", i, err);
fflush(stdout);
}
if((((err <= eps_sq) && (rel_prec == 0)) || ((err <= eps_sq*squarenorm) && (rel_prec == 1))) && i>0) {
finalize_solver(solver_field, nr_sf);
return(i);
}
f(v, p);
denom = scalar_prod(hatr, v, N, 1);
_div_complex(alpha, rho0, denom);
assign(s, r, N);
assign_diff_mul(s, v, alpha, N);
f(t, s);
omega = scalar_prod(t,s, N, 1);
d1 = square_norm(t, N, 1);
omega.re/=d1; omega.im/=d1;
assign_add_mul_add_mul(P, p, s, alpha, omega, N);
assign(r, s, N);
assign_diff_mul(r, t, omega, N);
rho1 = scalar_prod(hatr, r, N, 1);
if(fabs(rho1.re) < 1.e-25 && fabs(rho1.im) < 1.e-25) {
finalize_solver(solver_field, nr_sf);
return(-1);
}
_mult_assign_complex(nom, alpha, rho1);
_mult_assign_complex(denom, omega, rho0);
_div_complex(beta, nom, denom);
omega.re=-omega.re; omega.im=-omega.im;
assign_mul_bra_add_mul_ket_add(p, v, r, omega, beta, N);
rho0.re = rho1.re; rho0.im = rho1.im;
}
finalize_solver(solver_field, nr_sf);
return -1;
}
