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Make l1_norm_diff multithreaded too #4450

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Make l1_norm_diff multithreaded too #4450

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7a72c38
Clearer name for l2 Differ
roystgnr May 5, 2026
c2dbf11
Multithreaded l1_norm_diff
roystgnr May 5, 2026
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43 changes: 32 additions & 11 deletions src/numerics/numeric_vector.C
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Original file line number Diff line number Diff line change
Expand Up @@ -617,28 +617,28 @@ Real NumericVector<T>::l2_norm_diff (const NumericVector<T> & v) const
{
libmesh_assert(this->compatible(v));

struct Differ {
struct L2Differ {
const NumericVector<T> & v1, & v2;
Real norm_sq;

Differ (const NumericVector<T> & v1in,
const NumericVector<T> & v2in) :
L2Differ (const NumericVector<T> & v1in,
const NumericVector<T> & v2in) :
v1(v1in), v2(v2in), norm_sq(0) {}

Differ (Differ & other, Threads::split) :
L2Differ (L2Differ & other, Threads::split) :
v1(other.v1), v2(other.v2), norm_sq(0) {}

void operator()(const IntRange<numeric_index_type> & index_range) {
for (const auto i : index_range)
norm_sq += TensorTools::norm_sq(v1(i) - v2(i));
}

void join(const Differ & other) {
void join(const L2Differ & other) {
norm_sq += other.norm_sq;
}
};

Differ differ(*this, v);
L2Differ differ(*this, v);

Threads::parallel_reduce(make_range(this->first_local_index(), this->last_local_index()), differ);

Expand All @@ -654,13 +654,34 @@ Real NumericVector<T>::l1_norm_diff (const NumericVector<T> & v) const
{
libmesh_assert(this->compatible(v));

Real norm = 0;
for (const auto i : make_range(this->first_local_index(), this->last_local_index()))
norm += libMesh::l1_norm_diff((*this)(i), v(i));
struct L1Differ {
const NumericVector<T> & v1, & v2;
Real norm;

this->comm().sum(norm);
L1Differ (const NumericVector<T> & v1in,
const NumericVector<T> & v2in) :
v1(v1in), v2(v2in), norm(0) {}

return norm;
L1Differ (L1Differ & other, Threads::split) :
v1(other.v1), v2(other.v2), norm(0) {}

void operator()(const IntRange<numeric_index_type> & index_range) {
for (const auto i : index_range)
norm += libMesh::l1_norm_diff(v1(i), v2(i));
}

void join(const L1Differ & other) {
norm += other.norm;
}
};

L1Differ differ(*this, v);

Threads::parallel_reduce(make_range(this->first_local_index(), this->last_local_index()), differ);

this->comm().sum(differ.norm);

return differ.norm;
}


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