simex(model, SIMEXvariable, measurement.error, lambda = c(0.5, 1, 1.5,2), B = 100, fitting.method = "quadratic",  jackknife.estimation = "quadratic", asymptotic = TRUE)
如上，这个simex函数里第一个参数是model，它举的例子是lm(y~x1+x2)。但是如果R语言没有现成的拟合函数要怎么输入这个模型呢？