left_scale_inplace.hpp

来自「矩阵运算源码最新版本」· HPP 代码 · 共 74 行

// Software License for MTL
// 
// Copyright (c) 2007 The Trustees of Indiana University. All rights reserved.
// Authors: Peter Gottschling and Andrew Lumsdaine
// 
// This file is part of the Matrix Template Library
// 
// See also license.mtl.txt in the distribution.

#ifndef MTL_LEFT_SCALE_INPLACE_INCLUDE
#define MTL_LEFT_SCALE_INPLACE_INCLUDE

#include <boost/numeric/mtl/mtl_fwd.hpp>
#include <boost/numeric/mtl/utility/tag.hpp>
#include <boost/numeric/mtl/operation/assign_each_nonzero.hpp>
#include <boost/numeric/mtl/operation/mult.hpp>

#include <boost/lambda/lambda.hpp>


namespace mtl {


/// Scale collection \p c from left with scalar factor \p alpha; \p c is altered
template <typename Factor, typename Collection>
void left_scale_inplace(const Factor& alpha, tag::scalar, Collection& c)
{
    using namespace boost::lambda;
    assign_each_nonzero(c, alpha * _1);
}

template <typename Factor, typename Matrix>
void left_scale_inplace(const Factor& alpha, tag::matrix, Matrix& m, tag::matrix)
{
    using mtl::swap;

    Matrix tmp(num_rows(m), num_cols(m));
    mult(alpha, m, tmp);
    swap(m, tmp);
}

template <typename Factor, typename Vector>
void left_scale_inplace(const Factor& alpha, tag::matrix, Vector& v, tag::vector)
{
    using mtl::swap;

    Vector tmp(size(v));
    mult(alpha, v, tmp);
    swap(v, tmp);
}

/// Scale collection \p c from left with matrix factor \p alpha; \p c is altered
template <typename Factor, typename Collection>
void left_scale_inplace(const Factor& alpha, tag::matrix, Collection& c)
{
    // Need to dispatch further to use different constructors for temporary
    left_scale_inplace(alpha, tag::matrix(), c, typename traits::category<Collection>::type());
}

/// Scale collection \p c from left with factor \p alpha; \p c is altered
template <typename Factor, typename Collection>
void left_scale_inplace(const Factor& alpha, Collection& c)
{
    // Dispatch between scalar and matrix factors
    left_scale_inplace(alpha, typename traits::category<Factor>::type(), c);
}




} // namespace mtl

#endif // MTL_LEFT_SCALE_INPLACE_INCLUDE