dot method

List dot(List list1, List list2)

Function returns the dot product of two arrays. For 2-D vectors, it is the equivalent to matrix multiplication. For 1-D arrays, it is the inner product of the vectors. For N-dimensional arrays, it is a sum product over the last axis of a and the second-last axis of b.

var dot = m2d.dot([[1,2],[3,4]], [[11,12],[13,14]])
print(dot);
//[[37, 40], [85, 92]]

Implementation

List dot(List list1, List list2) {
  if (!_checkArray(list1) || !_checkArray(list1)) {
    throw ('Uneven array dimension');
  }
  var list1Shape = shape(list1);
  var list2Shape = shape(list2);
  if (list1Shape.length < 2 || list2Shape.length < 2) {
    throw new Exception(
        'Currently support 2D operations or put that values inside a list of list');
  }

  if (list1Shape[1] != list2Shape[0]) {
    throw new Exception('Shapes not aligned');
  }
  // todo needs to use zero fun
  var result = new List<num>.filled(list1.length, 0)
      .map((e) => List<num>.filled(list2[0].length, 0))
      .toList();
  // list1 x list2 matrix
  for (var r = 0; r < list1.length; r++) {
    for (var c = 0; c < list2[0].length; c++) {
      for (var i = 0; i < list1[0].length; i++) {
        result[r][c] += list1[r][i] * list2[i][c];
      }
    }
  }
  return result;
}