blockDiag function

Matrix blockDiag(List arrays)

Implementation

Matrix blockDiag(List arrays) {
  if (arrays.isEmpty) {
    return Matrix.empty();
  } else if (arrays.length == 1) {
    if (arrays.first is num) {
      return Matrix.scalar(arrays.first, 1);
    } else if (arrays.first is Matrix) {
      return arrays.first;
    }
  }

  List transformed = [];

  for (var element in arrays) {
    transformed.add(atLeast2D(element));
  }

  int rows = 0;
  int columns = 0;

  for (var element in transformed) {
    rows = rows + element.rowsNum as int;
    columns = columns + element.columnsNum as int;
  }

  List<double> output = List.filled(rows * columns, 0);
  int cellNumber = 0;

  for (var matrix in transformed) {
    matrix.forEach((vector) {
      vector.forEach((scalar) {
        output[cellNumber] = scalar;
        cellNumber = cellNumber + 1;
      });

      cellNumber = cellNumber + columns - vector.length as int;
    });

    cellNumber = cellNumber + matrix.columnsNum as int;
  }

  return Matrix.fromFlattenedList(output, rows, columns);
}