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Normalisation fixes #3482

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dschwoerer wants to merge 3 commits into from
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Normalisation fixes #3482

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b4acce5
Ensure everything gets reset
dschwoerer Aug 28, 2026
c6c1253
Add option to normalise by multiplication instead of division
dschwoerer Aug 28, 2026
ce436fe
Merge branch 'next' of https://github.com/boutproject/BOUT-dev into h…
dschwoerer Aug 28, 2026
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9 changes: 9 additions & 0 deletions include/bout/coordinates.hxx
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Original file line number Diff line number Diff line change
Expand Up @@ -564,17 +564,26 @@ std::string parallelSliceFieldName(std::string_view field, int offset);
/// tensor, which is multiplied by the normalisation factor.
struct MetricNormaliser {
std::optional<BoutReal> g = std::nullopt;
bool g_mul = false;
std::optional<BoutReal> g11 = std::nullopt;
bool g11_mul = false;
std::optional<BoutReal> g22 = std::nullopt;
bool g22_mul = false;
std::optional<BoutReal> g33 = std::nullopt;
bool g33_mul = false;
std::optional<BoutReal> g12 = std::nullopt;
bool g12_mul = false;
std::optional<BoutReal> g13 = std::nullopt;
bool g13_mul = false;
std::optional<BoutReal> g23 = std::nullopt;
bool g23_mul = false;
std::optional<BoutReal> dx = std::nullopt;
std::optional<BoutReal> dy = std::nullopt;
std::optional<BoutReal> dz = std::nullopt;
std::optional<BoutReal> J = std::nullopt;
bool J_mul = false;
std::optional<BoutReal> Bxy = std::nullopt;
bool Bxy_mul = false;
};

#endif // BOUT_COORDINATES_H
35 changes: 28 additions & 7 deletions src/mesh/coordinates.cxx
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Expand Up @@ -1313,16 +1313,32 @@ void Coordinates::normaliseMetric(const MetricNormaliser& norm) {

if (norm.J.has_value()) {
if (J().hasParallelSlices()) {
setJ(FieldMetricParallel{J() / *norm.J});
if (norm.J_mul) {
setJ(FieldMetricParallel{J() * *norm.J});
} else {
setJ(FieldMetricParallel{J() / *norm.J});
}
} else {
setJ(J() / *norm.J);
if (norm.J_mul) {
setJ(J() * *norm.J);
} else {
setJ(J() / *norm.J);
}
}
}
if (norm.Bxy.has_value()) {
if (Bxy().hasParallelSlices()) {
setBxy(FieldMetricParallel{Bxy() / *norm.Bxy});
if (norm.Bxy_mul) {
setBxy(FieldMetricParallel{Bxy() * *norm.Bxy});
} else {
setBxy(FieldMetricParallel{Bxy() / *norm.Bxy});
}
} else {
setBxy(Bxy() / *norm.Bxy);
if (norm.Bxy_mul) {
setBxy(Bxy() * *norm.Bxy);
} else {
setBxy(Bxy() / *norm.Bxy);
}
}
}
if (norm.dx.has_value()) {
Expand All @@ -1334,7 +1350,7 @@ void Coordinates::normaliseMetric(const MetricNormaliser& norm) {
if (norm.dz.has_value()) {
setDz(dz() / *norm.dz);
}
invalidateMetricCaches();
recalculateAndReset(false, false);
if (norm.g.has_value() or norm.g22.has_value()) {
if (Bxy().isFci()) {
// No we compute g_22_* - they must not be cleared. If they get
Expand All @@ -1343,9 +1359,14 @@ void Coordinates::normaliseMetric(const MetricNormaliser& norm) {
g_22_ylow();
g_22_yhigh();
ASSERT2(_g_22_ylow.has_value());
(*_g_22_ylow) /= g22;
ASSERT2(_g_22_yhigh.has_value());
(*_g_22_yhigh) /= g22;
if (norm.g.has_value() ? norm.g_mul : norm.g22_mul) {
(*_g_22_ylow) *= g22;
(*_g_22_yhigh) *= g22;
} else {
(*_g_22_ylow) /= g22;
(*_g_22_yhigh) /= g22;
}
}
}
}
52 changes: 34 additions & 18 deletions src/mesh/metric_tensor.cxx
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Expand Up @@ -152,40 +152,56 @@ auto ContravariantMetricTensor::inverse(const std::string& region, bool communic
template <class F>
void MetricTensor::normaliseMetric(const MetricNormaliser& norm, const F& op) {
if (norm.g.has_value()) {
op(g11_m, norm.g);
op(g22_m, norm.g);
op(g33_m, norm.g);
op(g12_m, norm.g);
op(g13_m, norm.g);
op(g23_m, norm.g);
op(g11_m, norm.g, norm.g_mul);
op(g22_m, norm.g, norm.g_mul);
op(g33_m, norm.g, norm.g_mul);
op(g12_m, norm.g, norm.g_mul);
op(g13_m, norm.g, norm.g_mul);
op(g23_m, norm.g, norm.g_mul);
} else {
op(g11_m, norm.g11);
op(g22_m, norm.g22);
op(g33_m, norm.g33);
op(g12_m, norm.g12);
op(g13_m, norm.g13);
op(g23_m, norm.g23);
op(g11_m, norm.g11, norm.g11_mul);
op(g22_m, norm.g22, norm.g22_mul);
op(g33_m, norm.g33, norm.g33_mul);
op(g12_m, norm.g12, norm.g12_mul);
op(g13_m, norm.g13, norm.g13_mul);
op(g23_m, norm.g23, norm.g23_mul);
}
}

void ContravariantMetricTensor::normaliseMetric(const MetricNormaliser& norm) {
MetricTensor::normaliseMetric(norm, [](FieldMetric& f, auto fac) {
MetricTensor::normaliseMetric(norm, [](FieldMetric& f, auto fac, bool fac_mul) {
if (fac.has_value()) {
if (f.hasParallelSlices()) {
f.asField3DParallel() *= fac.value();
if (fac_mul) {
f.asField3DParallel() /= fac.value();
} else {
f.asField3DParallel() *= fac.value();
}
} else {
f *= fac.value();
if (fac_mul) {
f /= fac.value();
} else {
f *= fac.value();
}
}
}
});
}
void CovariantMetricTensor::normaliseMetric(const MetricNormaliser& norm) {
MetricTensor::normaliseMetric(norm, [](FieldMetric& f, auto fac) {
MetricTensor::normaliseMetric(norm, [](FieldMetric& f, auto fac, bool fac_mul) {
if (fac.has_value()) {
if (f.hasParallelSlices()) {
f.asField3DParallel() /= fac.value();
if (fac_mul) {
f.asField3DParallel() *= fac.value();
} else {
f.asField3DParallel() /= fac.value();
}
} else {
f /= fac.value();
if (fac_mul) {
f *= fac.value();
} else {
f /= fac.value();
}
}
}
});
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12 changes: 8 additions & 4 deletions src/mesh/tokamak_coordinates.cxx
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Expand Up @@ -81,14 +81,18 @@ MetricNormaliser TokamakOrFCIMetricNormaliser(const Mesh* mesh, BoutReal Bnorm,
if (mesh->isFci()) {
return {.g{SQ(rho_s0)}, .J{rho_s0 * rho_s0 * rho_s0}, .Bxy{Bnorm}};
}
return {.g11{1 / SQ(Bnorm * rho_s0)},
return {.g11{SQ(Bnorm * rho_s0)},
.g11_mul{true},

@github-actions github-actions Bot Aug 28, 2026

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warning: braces around scalar initializer [clang-diagnostic-braced-scalar-init]

Suggested change
.g11_mul{true},
.g11_mul true,

@dschwoerer dschwoerer Aug 28, 2026

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Not sure what clang-tidy is trying to do here, but g++ 15.2.0 is not happy with the suggested change.

.g22{SQ(rho_s0)},
.g33{SQ(rho_s0)},
.g12{1 / Bnorm},
.g13{1 / Bnorm},
.g12{Bnorm},
.g12_mul{true},
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dschwoerer marked this conversation as resolved.
Comment on lines +88 to +89

@ZedThree ZedThree Sep 1, 2026

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I don't understand this at all -- why is this not equivalent? Is it just loss of precision?

@dschwoerer dschwoerer Sep 2, 2026

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Yes, and that seems to cause the failures in Hermes-3. If you think we should not do this, and just update the expected results, then we can do that, too. But I thought it might be good if we do not change results without a somewhat good reason, and the _mul additions do not seem like a huge addition of code.

.g13{Bnorm},
.g13_mul{true},
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.g23{SQ(rho_s0)},
.dx{rho_s0 * rho_s0 * Bnorm},
.J{rho_s0 / Bnorm},
.J{Bnorm / rho_s0},
.J_mul{true},
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.Bxy{Bnorm}};
}

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