r-预测.HoltWinters没有被映射到C++中

根据示例代码，我试图使用c++和RInside运行预测方法，但我得到了Read 100 items Exception caught: not a matrix

有人能看看我的密码吗。

  #include <RInside.h>
    int main ( int argc, char **argv) {
        try {
            // create an embedded R instance 
            RInside R ( argc, argv);
            std::string txt =
                "rain <- scan("http://robjhyndman.com/tsdldata/hurst/precip1.dat",skip=1);"
                "rainseries <- ts(rain,start=c(1813));"
                "rainseriesforecasts <- HoltWinters(rainseries, beta=FALSE, gamma=FALSE);"
                "suppressMessages(require(forecast));";
            R.parseEvalQ(txt); // eval command, no return
            Rcpp::NumericMatrix M((SEXP)R.parseEval("rainseriesforecasts2 <- forecast.HoltWinters(rainseriesforecasts, h=8)"));
            Rcpp::StringVector cnames( (SEXP) R.parseEval("colnames(rainseriesforecasts2)"));
            Rcpp::StringVector rnames( (SEXP) R.parseEval("rownames(rainseriesforecasts2)"));
            std::cout << "nnAnd now from C++nnttt";
            for (int i=0; i<cnames.size(); i++) {
                std::cout << std::setw(11) << cnames[i] << "t";
            }
            std::cout << std::endl;
            for (int i=0; i<rnames.size(); i++) {
                std::cout << std::setw(16) << rnames[i] << "t";
                for (int j=0; j<cnames.size(); j++) {
                    std::cout << std::setw(11) << M(i,j) << "t";
                }
                std::cout << std::endl;
            }
            std::cout << std::endl;
        } catch(std::exception& ex) {
            std::cerr << "Exception caught: " << ex.what() << std::endl;
        } catch(...) {
            std::cerr << "Unknown exception caught" << std::endl;
        }
    }