load camera parameters from yml file cpp

edit

I saved the CameraParams which is defined in Opencv Stitching Detailed sample. Here is the how camera parameter structure looks like:

struct CV_EXPORTS CameraParams
 {
    CameraParams();
    CameraParams(const CameraParams& other);
    const CameraParams& operator =(const CameraParams& other);
    Mat K() const;

    double focal; // Focal length
    double aspect; // Aspect ratio
    double ppx; // Principal point X
    double ppy; // Principal point Y
    Mat R; // Rotation
    Mat t; // Translation
};

I wrote the camera Parameters calculated from the stitching_detailed.cpp using the following code:

  <cameraParams> cameras;
  FileStorage fs(fileName, FileStorage::WRITE);
  fs << "K" << cameras.K();
  fs << "R" << cameras.R;
  fs << "t" << cameras.t;
  fs << "ppx" << cameras.ppx;
  fs << "ppy" << cameras.ppy;
  fs << "focal" << cameras.focal;
  fs << "aspect" << cameras.aspect;
  fs.release();

Here is how the file content looked like:

  %YAML:1.0
  ---
  K: !!opencv-matrix
    rows: 3
    cols: 3
    dt: d
    data: [ 2.4125938056164614e+003, 0., 447., 0.,
        2.4125938056164614e+003, 3.3550000000000000e+002, 0., 0., 1. ]
  R: !!opencv-matrix
    rows: 3
    cols: 3
    dt: f
    data: [ -9.67408061e-001, 7.91518241e-002, -2.40534484e-001,
        -4.17553373e-002, -9.86752093e-001, -1.56770796e-001,
        -2.49756604e-001, -1.41617730e-001, 9.57896829e-001 ]
  t: !!opencv-matrix
    rows: 3
    cols: 1
    dt: d
    data: [ 0., 0., 0. ]
  ppx: 447.
  ppy: 3.3550000000000000e+002
  focal: 2.4125938056164614e+003
  aspect: 1.

How can I now load these camera parameters to initialize CameraParams. This is the read function I was using:

Mat K, R, t;
double ppx, ppy, focal, aspect;
FileStorage fs(fileName, FileStorage::READ);
fs["K"] >> K;
fs["R"] >> R;
fs["t"] >> t;
fs["ppx"] >> ppx;
fs["ppx"] >> ppy;
fs["focal"] >> focal;
fs["aspect"] >> aspect;
camerasTest[i].K() = (Mat)K;
camerasTest[i].R = R;
camerasTest[i].t = t;
camerasTest[i].ppx = (double)ppx;
camerasTest[i].ppy = (double)ppy;
camerasTest[i].focal = (double)focal;
camerasTest[i].aspect = (double)aspect;
fs.release()

but this gives Run time error. So what transformation can be done