double cvGetReal1D(CvArr* arr, int idx0) {
    void *fptr;
    double retval;

    fptr = dlsym(_Chcv_handle, "cvGetReal1D_chdl");
    if(fptr == NULL) {
        fprintf(_stderr, "Error: %s(): dlsym(): %s\n", __func__,  dlerror());
        return -1;
    }
    dlrunfun(fptr, &retval, cvGetReal1D, arr, idx0);
    return retval;
}
