void ax3len(int nxl, int nyl, int nzl) {
    void *fptr;

    fptr = dlsym(_Chdislin_handle, "ax3len_chdl");
    if(fptr == NULL) {
        fprintf(_stderr, "Error: %s(): dlsym(): %s\n", __func__,  dlerror());
        return;
    }
    dlrunfun(fptr, NULL, ax3len, nxl, nyl, nzl);
}