demos/mix_eigen_and_c/example.c

// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2009 Benoit Jacob <jacob.benoit.1@gmail.com>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#include "binary_library.h"
#include "stdio.h"

void demo_MatrixXd() {
  struct C_MatrixXd *matrix1, *matrix2, *result;
  printf("*** demo_MatrixXd ***\n");

  matrix1 = MatrixXd_new(3, 3);
  MatrixXd_set_zero(matrix1);
  MatrixXd_set_coeff(matrix1, 0, 1, 2.5);
  MatrixXd_set_coeff(matrix1, 1, 0, 1.4);
  printf("Here is matrix1:\n");
  MatrixXd_print(matrix1);

  matrix2 = MatrixXd_new(3, 3);
  MatrixXd_multiply(matrix1, matrix1, matrix2);
  printf("Here is matrix1*matrix1:\n");
  MatrixXd_print(matrix2);

  MatrixXd_delete(matrix1);
  MatrixXd_delete(matrix2);
}

// this helper function takes a plain C array and prints it in one line
void print_array(double *array, int n) {
  struct C_Map_MatrixXd *m = Map_MatrixXd_new(array, 1, n);
  Map_MatrixXd_print(m);
  Map_MatrixXd_delete(m);
}

void demo_Map_MatrixXd() {
  struct C_Map_MatrixXd *map;
  double array[5];
  int i;
  printf("*** demo_Map_MatrixXd ***\n");

  for (i = 0; i < 5; ++i) array[i] = i;
  printf("Initially, the array is:\n");
  print_array(array, 5);

  map = Map_MatrixXd_new(array, 5, 1);
  Map_MatrixXd_add(map, map, map);
  Map_MatrixXd_delete(map);

  printf("Now the array is:\n");
  print_array(array, 5);
}

int main() {
  demo_MatrixXd();
  demo_Map_MatrixXd();
}