expand.h

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#ifndef __SABLIB_EXPAND_H__
#define __SABLIB_EXPAND_H__
 
#include <stdexcept>
#include <Eigen/Eigen>
 
namespace sablib {

template <typename Derived>
const typename Derived::PlainObject ExpandBoundaries(const Eigen::MatrixBase<Derived> & y, const unsigned int n)
{
    // Although parameters are received as MatrixBase<Derived>, only vector classes are allowed.
    // Others will be rejected at compile time.
    static_assert(Derived::IsVectorAtCompileTime, "Error: y is not vector.");
 
    typename Derived::PlainObject result(y.size() + 2 * n);
 
    if(y.cols() == 1) {
        result.block(0, 0, n, 1).fill(y(0));
        result.block(result.size() - n, 0, n, 1).fill(y(y.size() - 1));
        result.block(n, 0, y.size(), 1) = y;
    }
    else if(y.rows() == 1) {
        result.block(0, 0, 1, n).fill(y(0));
        result.block(0, result.size() - n, 1, n).fill(y(y.size() - 1));
        result.block(0, n, 1, y.size()) = y;
    }
 
    return result;
}

template <typename Derived>
const typename Derived::PlainObject TrimBoundaries(const Eigen::MatrixBase<Derived> & y, const unsigned int n)
{
    // Although parameters are received as MatrixBase<Derived>, only vector classes are allowed.
    // Others will be rejected at compile time.
    static_assert(Derived::IsVectorAtCompileTime, "Error: y is not vector.");
 
    if(y.size() < 2 * n) {
        throw std::invalid_argument("TrimBoubdaries(): n is too large.");
    }
 
    if(y.cols() == 1) {
        return y.block(n, 0, y.size() - 2 * n, 1);
    }
    else if(y.rows() == 1) {
        return y.block(0, n, 1, y.size() - 2 * n);
    }
}
 
}; // namespace sablib
 
#endif // __SABLIB_EXPAND_H__