Constructing a Matrix

    There are several ways to construct a Matrix object. To construct an empty matrix, use the following code:

Matrix matrix = new Matrix(3,2);

    This will construct an empty matrix of three rows and two columns, which contains only zeros. This matrix is described in Equation 2.3.

Equation 2.3: An Empty Matrix

    You can also construct a matrix using a two dimensional array, which allows you to initialize the cells of the matrix in the declaration. The following code creates an initialized 3x2 matrix.

double matrixData[][] = {
  {1.0,2.0,3.0},
  {4.0,5.0,6.0}
};
		
Matrix matrix = new Matrix(matrixData);

    This matrix is described in Equation 2.4.

Equation 2.4: An Initialized Matrix

    Matrixes can also be created using a single dimensional array. A single dimensional array can be used to create a row or a column matrix. Row and column matrixes contain either a single row or a single column, respectively. These matrixes are also called vectors. The following code can be used to create a row matrix.

double matrixData[] = {1.0,2.0,3.0,4.0};
Matrix matrix = Matrix.createRowMatrix(matrixData);

    This will create a matrix that contains a single row. This matrix is described in Equation 2.5.

Equation 2.5: A Row Matrix/Vector

    It is also possible to create a column matrix. This matrix takes a single dimensional array, just as before; however, this time a matrix with a single column is created. The code to do this is shown here.

double matrixData[] = {1.0,2.0,3.0,4.0};
Matrix matrix = Matrix.createColumnMatrix(matrixData);

    This matrix is described in Equation 2.6.

Equation 2.6: A Column Matrix/Vector

    In the next section you will see how mathematical operations can be performed on one or more matrixes.