sparse_inf_norms.hpp

// Copyright (c) Sleipnir contributors
 
#pragma once
 
#include <algorithm>
 
#include <Eigen/Core>
#include <Eigen/SparseCore>
 
namespace slp {
 
template <typename Derived>
auto sparse_inf_norms(const Eigen::SparseCompressedBase<Derived>& mat)
    -> Eigen::Vector<typename Derived::Scalar, Eigen::Dynamic> {
  using Scalar = typename Derived::Scalar;
  using DenseVector = Eigen::Vector<Scalar, Eigen::Dynamic>;
 
  DenseVector norms = DenseVector::Zero(mat.rows());
  for (int k = 0; k < mat.outerSize(); ++k) {
    for (typename Derived::InnerIterator it{mat, k}; it; ++it) {
      using std::abs;
      norms[it.row()] = std::max(norms[it.row()], abs(it.value()));
    }
  }
 
  return norms;
}
 
}  // namespace slp