我在R中使用ugarch来预测时间序列数据：Purchastimeseries。 我解释了下面描述的问题。有人知道为什么吗？
purchasetimeseries
[,1]
2013-07-01 22533121
2013-07-02 29624840
2013-07-03 22525940
2013-07-04 32111643
......
2014-08-31 27609385
> attSpec <- ugarchspec(variance.model = list(model="fGARCH", garchOrder=c(1,1)), mean.model=list(armaOrder=c(3,3)), distribution.model = 'std')
> attGarch <- ugarchfit(spec=attSpec, data=purchasetimeseries)
Error in solve.default(res$hessian * n.used) : Lapack routine dgesv: system is exactly singular
In arima(data, order = c(modelinc[2], 0, modelinc[3]), include.mean = modelinc[1], :possible convergence problem: optim gave code = 1