public static void matrixXvector(DenseMatrix64F dest, DenseMatrix64F src, DenseMatrix64F srcMatrix, int from, int to, int from2, int to2) {

        double[] destData = dest.getData();
        double[] srcData = src.getData();
        double[] srcMatrixData = srcMatrix.getData();
        int matrixWidth = srcMatrix.numCols;

        for (int b=from; b<to; b++) {
            for (int a=from2; a<to2; a++) {
                destData[b] += srcData[a] * srcMatrixData[a+b*matrixWidth];
            }
        }
    }