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BCGSTAB: return the iterate with the smallest residual #2933

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Merged
bigfooted merged 9 commits into from
Oct 13, 2026
Merged

BCGSTAB: return the iterate with the smallest residual #2933

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d89a5f8
BCGSTAB: return the iterate with the smallest residual
bigfooted Sep 27, 2026
e08ba03
clang
bigfooted Sep 27, 2026
eaed58f
Merge branch 'develop' into fix_bcgstab
bigfooted Oct 4, 2026
2b7949c
Merge branch 'develop' into fix_bcgstab
bigfooted Oct 9, 2026
2f2ace0
Merge branch 'develop' into fix_bcgstab
bigfooted Oct 12, 2026
c81e8ff
guard initialization
bigfooted Oct 12, 2026
d2201a8
update regressions
bigfooted Oct 13, 2026
587d8d1
Merge branch 'develop' into fix_bcgstab
bigfooted Oct 13, 2026
8d3ac70
Merge branch 'develop' into fix_bcgstab
bigfooted Oct 13, 2026
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5 changes: 3 additions & 2 deletions Common/include/linear_algebra/CSysSolve.hpp
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Expand Up @@ -109,8 +109,9 @@ class CSysSolve {
mutable VectorType p; /*!< \brief Direction in CG and BCGSTAB. */
mutable VectorType z; /*!< \brief Preconditioned residual/direction in CG/BCGSTAB. */

mutable VectorType r_0; /*!< \brief The "arbitrary" vector in BCGSTAB. */
mutable VectorType v; /*!< \brief BCGSTAB "v" vector (v = A * M^-1 * p). */
mutable VectorType r_0; /*!< \brief The "arbitrary" vector in BCGSTAB. */
mutable VectorType v; /*!< \brief BCGSTAB "v" vector (v = A * M^-1 * p). */
mutable VectorType x_best; /*!< \brief BCGSTAB iterate with the smallest residual. */

mutable bool ritz_failed = false;
mutable unsigned long k = 0, k_new = 0;
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14 changes: 14 additions & 0 deletions Common/src/linear_algebra/CSysSolve.cpp
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Expand Up @@ -1087,6 +1087,7 @@ unsigned long CSysSolve<ScalarType>::BCGSTAB_LinSolver(const CSysVector<ScalarTy
p.Initialize(nBlk, nBlkDomain, nVar, nullptr);
v.Initialize(nBlk, nBlkDomain, nVar, nullptr);
z.Initialize(nBlk, nBlkDomain, nVar, nullptr);
if (config->GetComm_Level() == COMM_FULL) x_best.Initialize(nBlk, nBlkDomain, nVar, nullptr);

bcg_ready = true;
}
Expand Down Expand Up @@ -1135,6 +1136,8 @@ unsigned long CSysSolve<ScalarType>::BCGSTAB_LinSolver(const CSysVector<ScalarTy
/*--- Initialization ---*/

ScalarType alpha = 1.0, omega = 1.0, rho = 1.0, rho_prime = 1.0;
ScalarType norm_best = norm_r;
if (config->GetComm_Level() == COMM_FULL) x_best = x;
p = ScalarType(0.0);
v = ScalarType(0.0);
r_0 = r;
Expand Down Expand Up @@ -1195,6 +1198,10 @@ unsigned long CSysSolve<ScalarType>::BCGSTAB_LinSolver(const CSysVector<ScalarTy
/*--- Check if solution has converged, else output the relative residual if necessary ---*/

norm_r = r.norm();
if (norm_r < norm_best) {
norm_best = norm_r;
x_best = x;
}
if (norm_r < tol * norm0) break;
if (((monitoring) && (masterRank)) && ((i + 1) % monitorFreq == 0)) {
SU2_OMP_MASTER
Expand All @@ -1204,6 +1211,13 @@ unsigned long CSysSolve<ScalarType>::BCGSTAB_LinSolver(const CSysVector<ScalarTy
}
}

/*--- BCGSTAB does not reduce the residual monotonically, return the best iterate. ---*/

if ((config->GetComm_Level() == COMM_FULL) && (norm_r > norm_best)) {
x = x_best;
norm_r = norm_best;
}

/*--- Recalculate final residual (this should be optional) ---*/

if ((monitoring) && (config->GetComm_Level() == COMM_FULL)) {
Expand Down
6 changes: 3 additions & 3 deletions TestCases/hybrid_regression.py
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Expand Up @@ -80,7 +80,7 @@ def main():
wedge.cfg_dir = "euler/wedge"
wedge.cfg_file = "inv_wedge_HLLC.cfg"
wedge.test_iter = 20
wedge.test_vals = [-0.480786, 5.329367, -0.244869, 0.043126]
wedge.test_vals = [ 0.036140, 6.976887, -0.219795, 0.055341]
test_list.append(wedge)

# ONERA M6 Wing
Expand Down Expand Up @@ -170,7 +170,7 @@ def main():
rae2822_sa.cfg_dir = "rans/rae2822"
rae2822_sa.cfg_file = "turb_SA_RAE2822.cfg"
rae2822_sa.test_iter = 20
rae2822_sa.test_vals = [-2.639525, -4.027096, 0.792680, 0.020549, 1000.000000]
rae2822_sa.test_vals = [-2.913915, -5.160924, 0.801922, 0.019587, 1000.000000]
test_list.append(rae2822_sa)

# RAE2822 SST
Expand Down Expand Up @@ -452,7 +452,7 @@ def main():
inc_turb_naca0012.cfg_dir = "incomp_rans/naca0012"
inc_turb_naca0012.cfg_file = "naca0012.cfg"
inc_turb_naca0012.test_iter = 20
inc_turb_naca0012.test_vals = [-4.758114, -10.974548, -0.000004, -0.028637, 5.000000, -4.081478, 2.000000, -4.490126]
inc_turb_naca0012.test_vals = [-4.758114, -10.974548, -0.000006, -0.028637, 4.000000, -4.016988, 2.000000, -4.487046]
test_list.append(inc_turb_naca0012)

# NACA0012, SST_SUST
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16 changes: 8 additions & 8 deletions TestCases/parallel_regression.py
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Expand Up @@ -156,7 +156,7 @@ def main():
invwedge_roe.cfg_dir = "nonequilibrium/invwedge"
invwedge_roe.cfg_file = "invwedge_roe.cfg"
invwedge_roe.test_iter = 10
invwedge_roe.test_vals = [-1.158437, -1.683200, -17.734417, -18.064156, -18.007526, 2.157771, 1.789407, 5.196450, 0.767270]
invwedge_roe.test_vals = [-0.856717, -1.381479, -16.733080, -17.063919, -17.006196, 2.492274, 1.625077, 5.504576, 1.052309]
invwedge_roe.test_vals_aarch64 = [-1.156325, -1.681088, -17.726749, -18.056513, -17.999860, 2.159488, 1.793498, 5.198638, 0.769831]
test_list.append(invwedge_roe)

Expand Down Expand Up @@ -463,7 +463,7 @@ def main():
rae2822_sa.cfg_dir = "rans/rae2822"
rae2822_sa.cfg_file = "turb_SA_RAE2822.cfg"
rae2822_sa.test_iter = 20
rae2822_sa.test_vals = [-2.888183, -5.136146, 0.788144, 0.019032, 1000.000000]
rae2822_sa.test_vals = [-3.032297, -5.144001, 0.789972, 0.019664, 1000.000000]
test_list.append(rae2822_sa)

# RAE2822 SST
Expand Down Expand Up @@ -949,15 +949,15 @@ def main():
turbmod_sa_bsl_rae2822.cfg_dir = "turbulence_models/sa/rae2822"
turbmod_sa_bsl_rae2822.cfg_file = "turb_SA_BSL_RAE2822.cfg"
turbmod_sa_bsl_rae2822.test_iter = 20
turbmod_sa_bsl_rae2822.test_vals = [-3.182935, -0.447793, -0.875861, -3.286652, 0.769925, 0.017709]
turbmod_sa_bsl_rae2822.test_vals = [-3.066175, -0.410328, -0.836186, -5.131450, 0.790218, 0.018113]
test_list.append(turbmod_sa_bsl_rae2822)

# SA Negative
turbmod_sa_neg_rae2822 = TestCase('turbmod_sa_neg_rae2822')
turbmod_sa_neg_rae2822.cfg_dir = "turbulence_models/sa/rae2822"
turbmod_sa_neg_rae2822.cfg_file = "turb_SA_NEG_RAE2822.cfg"
turbmod_sa_neg_rae2822.test_iter = 10
turbmod_sa_neg_rae2822.test_vals = [1.570952, 1.355242, -0.869320, 1.244343, 0.452923, 0.000000]
turbmod_sa_neg_rae2822.test_vals = [1.462498, 1.294317, -1.866969, 1.240402, 0.461990, 0.000000]
turbmod_sa_neg_rae2822.test_vals_aarch64 = [-1.345593, 1.448310, 1.208721, -0.846597, 1.248410, 0.489117, 0.000000]
test_list.append(turbmod_sa_neg_rae2822)

Expand All @@ -966,31 +966,31 @@ def main():
turbmod_sa_comp_rae2822.cfg_dir = "turbulence_models/sa/rae2822"
turbmod_sa_comp_rae2822.cfg_file = "turb_SA_COMP_RAE2822.cfg"
turbmod_sa_comp_rae2822.test_iter = 20
turbmod_sa_comp_rae2822.test_vals = [-3.192776, -0.471890, -0.893254, -5.190537, 0.777261, 0.017904]
turbmod_sa_comp_rae2822.test_vals = [-3.067270, -0.409333, -0.836419, -5.163006, 0.790775, 0.018091]
test_list.append(turbmod_sa_comp_rae2822)

# SA Edwards
turbmod_sa_edw_rae2822 = TestCase('turbmod_sa_edw_rae2822')
turbmod_sa_edw_rae2822.cfg_dir = "turbulence_models/sa/rae2822"
turbmod_sa_edw_rae2822.cfg_file = "turb_SA_EDW_RAE2822.cfg"
turbmod_sa_edw_rae2822.test_iter = 20
turbmod_sa_edw_rae2822.test_vals = [-3.198033, -0.439446, -0.883563, -3.899428, 0.786167, 0.017883]
turbmod_sa_edw_rae2822.test_vals = [-3.074021, -0.406573, -0.837105, -5.186866, 0.794308, 0.017860]
test_list.append(turbmod_sa_edw_rae2822)

# SA Compressibility and Edwards
turbmod_sa_comp_edw_rae2822 = TestCase('turbmod_sa_comp_edw_rae2822')
turbmod_sa_comp_edw_rae2822.cfg_dir = "turbulence_models/sa/rae2822"
turbmod_sa_comp_edw_rae2822.cfg_file = "turb_SA_COMP_EDW_RAE2822.cfg"
turbmod_sa_comp_edw_rae2822.test_iter = 20
turbmod_sa_comp_edw_rae2822.test_vals = [-2.943295, -0.168387, -0.632480, -5.127730, 0.802507, 0.020196]
turbmod_sa_comp_edw_rae2822.test_vals = [-3.070896, -0.339529, -0.812604, -5.279982, 0.809740, 0.019809]
test_list.append(turbmod_sa_comp_edw_rae2822)

# SA QCR
turbmod_sa_qcr_rae2822 = TestCase('turbmod_sa_qcr_rae2822')
turbmod_sa_qcr_rae2822.cfg_dir = "turbulence_models/sa/rae2822"
turbmod_sa_qcr_rae2822.cfg_file = "turb_SA_QCR_RAE2822.cfg"
turbmod_sa_qcr_rae2822.test_iter = 20
turbmod_sa_qcr_rae2822.test_vals = [-3.056565, -0.419621, -0.805532, -3.857890, 0.760796, 0.016908]
turbmod_sa_qcr_rae2822.test_vals = [-3.030070, -0.419207, -0.799348, -5.089007, 0.761556, 0.016831]
test_list.append(turbmod_sa_qcr_rae2822)

############################
Expand Down
4 changes: 2 additions & 2 deletions TestCases/serial_regression.py
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Expand Up @@ -236,7 +236,7 @@ def main():
rae2822_sa.cfg_dir = "rans/rae2822"
rae2822_sa.cfg_file = "turb_SA_RAE2822.cfg"
rae2822_sa.test_iter = 20
rae2822_sa.test_vals = [-3.131221, -5.161756, 0.778275, 0.019566, 1000.000000]
rae2822_sa.test_vals = [-3.119066, -5.151318, 0.777084, 0.019422, 1000.000000]
test_list.append(rae2822_sa)

# RAE2822 SST
Expand Down Expand Up @@ -508,7 +508,7 @@ def main():
inc_turb_naca0012.cfg_dir = "incomp_rans/naca0012"
inc_turb_naca0012.cfg_file = "naca0012.cfg"
inc_turb_naca0012.test_iter = 20
inc_turb_naca0012.test_vals = [-4.758064, -10.974498, -0.000003, -0.028654, 4, -6.049653, 2, -4.951206]
inc_turb_naca0012.test_vals = [-4.758064, -10.974498, -0.000003, -0.028654, 3.000000, -4.499423, 2.000000, -4.951202]
test_list.append(inc_turb_naca0012)

# NACA0012, SST_SUST
Expand Down
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