Java Jblas DoubleMatrix vector addition-CodePudding

I feel really stupid asking this, but I can't find a method for adding a row/vector to an index or a specific set of indices.

My current workaround is to getRows(int[]) then addiRowVector(DoubleMatrix) then put(Range rs, Range cs, DoubleMatrix x) : (get rows, add your vector, then put them back)

This seems like a backwards and costly implementation, is there any alternative? Is there something simple I'm missing?

Thanks in advance!

CodePudding user response：

For one row you can do it as in this piece of code using row number for example

void oneRow() {
    DoubleMatrix matrix = new DoubleMatrix(new double[][] {
            {11,12,13},
            {21,22,23},
            {31,32,33}});
    DoubleMatrix otherRow = new DoubleMatrix(new double[][] {{-11, -12, -13}});

    int rowNumber = 0;
    DoubleMatrix row = matrix.getRow(rowNumber);
    row.addiRowVector(otherRow);
    matrix.putRow(rowNumber, row);

    System.out.println(matrix);
}

as result you'll see

[0,000000, 0,000000, 0,000000; 21,000000, 22,000000, 23,000000; 31,000000, 32,000000, 33,000000]

for several rows you can use loop using row numbers array for example

void multipleRows() {
    DoubleMatrix matrix = new DoubleMatrix(new double[][] {
            {11,12,13},
            {21,22,23},
            {31,32,33}});

    int[] rowNumbers = {0, 2};
    DoubleMatrix otherRows = new DoubleMatrix(new double[][] {
            {-11, -12, -13},
            {-21, -22, -23}});
    int otherRowsNumber = 0;

    for (int r : rowNumbers) {
        DoubleMatrix row = matrix.getRow(r);
        row.addiRowVector(otherRows.getRow(otherRowsNumber  ));
        matrix.putRow(r, row);
    }
    System.out.println(matrix);
}

and here for result you see

[0,000000, 0,000000, 0,000000; 21,000000, 22,000000, 23,000000; 10,000000, 10,000000, 10,000000]