这是使用“”HydroMe包，nlsList 命令，对于一些数据分别会出现如下的错误提示，而有些数据又可以正常求解。实在分析不出来有错误的和可以正常求解的数据有什么本质区别~~那位大神帮帮忙吧，多谢啦~~
1）Error in nls(formula = formula, data = data, control = control) :
singular gradient
2）Error in qr.default(.swts * attr(rhs, "gradient" ) ) :
NA/NaN/Inf in foreign function call (arg 1)
3）Error in nlsModel(formula, mf, start, wts) :
singular gradient matrix at initial parameter estimates
4）Error in nls(formula = formula, data = data, control = control) :
step factor 0.000488281 reduced below 'minFactor' of 0.000976562
