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// Copyright (C) 2016-17 by the lazyten authors
// This file is part of lazyten.
// lazyten is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published
// by the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// lazyten is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with lazyten. If not, see <>.
#pragma once
#include <initializer_list>
#include <krims/GenMap.hh>
#include <lazyten/Constants.hh>
#include <lazyten/LazyMatrix_i.hh>
#include <lazyten/SmallVector.hh>
using namespace lazyten;
/** Matrix to represent a diagonal matrix by a vector.
* The vector can be changed via the update() function */
template <typename StoredMatrix>
class DiagonalUpdatable : public LazyMatrix_i<StoredMatrix> {
typedef LazyMatrix_i<StoredMatrix> base_type;
typedef typename base_type::stored_matrix_type stored_matrix_type;
typedef typename base_type::size_type size_type;
typedef typename base_type::scalar_type scalar_type;
typedef typename base_type::lazy_matrix_expression_ptr_type
/** Construct form diagonal vector */
DiagonalUpdatable(SmallVector<scalar_type> diagonal) : m_diagonal(diagonal) {}
/** Construct from initialiser list giving the diagonal */
DiagonalUpdatable(std::initializer_list<scalar_type> diagonal)
: m_diagonal(diagonal.size(), 1) {
size_t i = 0;
for (auto it = std::begin(diagonal); it != std::end(diagonal); ++it, ++i) {
m_diagonal(i, 0) = *it;
/** Number of rows */
size_type n_rows() const override { return m_diagonal.size(); }
/** Number of colums */
size_type n_cols() const override { return m_diagonal.size(); }
/** Element access */
scalar_type operator()(size_type row, size_type col) const override {
if (row == col) return m_diagonal[row];
return Constants<scalar_type>::zero;
/** Clone function */
lazy_matrix_expression_ptr_type clone() const override {
// return a copy enwrapped in the pointer type
return lazy_matrix_expression_ptr_type(new DiagonalUpdatable(*this));
/** \brief Provide an update mechanism */
void update(const krims::GenMap& m) override {
const auto& diagonal =<SmallVector<scalar_type>>("diagonal");
// check that we have no size changes
assert_size(diagonal.size(), m_diagonal.size());
// assign:
m_diagonal = diagonal;
// Note: One could override apply, mmult and extract_block for better
// performance in those matrix operations, but this is not required
// to get the basic functionality going.
// A n_rows times 1 vector of diagonal shifts
SmallVector<scalar_type> m_diagonal;