libigl_Martin/include/igl/repdiag.h

#ifndef IGL_REPDIAG_H
#define IGL_REPDIAG_H
#include "igl_inline.h"

#define EIGEN_YES_I_KNOW_SPARSE_MODULE_IS_NOT_STABLE_YET
#include <Eigen/Dense>
#include <Eigen/Sparse>

namespace igl
{
  // REPDIAG repeat a matrix along the diagonal a certain number of times, so
  // that if A is a m by n matrix and we want to repeat along the diagonal d
  // times, we get a m*d by n*d matrix B such that:
  // B( (k*m+1):(k*m+1+m-1), (k*n+1):(k*n+1+n-1)) = A 
  // for k from 0 to d-1
  //
  // Inputs:
  //   A  m by n matrix we are repeating along the diagonal. May be dense or
  //     sparse
  //   d  number of times to repeat A along the diagonal
  // Outputs:
  //   B  m*d by n*d matrix with A repeated d times along the diagonal,
  //     will be dense or sparse to match A
  //

  // Sparse version
  template <typename T>
  IGL_INLINE void repdiag(
    const Eigen::SparseMatrix<T>& A,
    const int d,
    Eigen::SparseMatrix<T>& B);
  // Dense version
  template <typename T>
  IGL_INLINE void repdiag(
    const Eigen::Matrix<T,Eigen::Dynamic,Eigen::Dynamic> & A,
    const int d,
    Eigen::Matrix<T,Eigen::Dynamic,Eigen::Dynamic> & B);
  // Wrapper with B as output
  template <class Mat>
  IGL_INLINE Mat repdiag(const Mat & A, const int d);
}

#ifdef IGL_HEADER_ONLY
#  include "repdiag.cpp"
#endif

#endif