fitvalue = fitted(nls.sol)
R2 = 1-sum((rd$SKIN-fitvalue)^2)/sum((rd$SKIN-mean(rd$SKIN))^2)
ME=sum(rd$SKIN-fitvalue)/ length(rd$SKIN)
MAE= sum(abs(rd$SKIN-fitvalue))/ length(rd$SKIN)
TRE= sum(rd$SKIN-fitvalue)/sum(fitvalue)*100
MSE= sum((rd$SKIN-fitvalue)/ fitvalue)/ length(rd$SKIN) *100
MPSE= sum(abs(rd$SKIN-fitvalue)/ fitvalue)/ length(rd$SKIN) *100
请问怎么样能把这些公式整合fuction{},这样不用一个一个的求了
而且function函数中可以改变rd$SKIN这个变量，在另外nls.sol<-nls(STEM~a*DBH^b,data=rd,start=list(a=0.01,b=2))，nls.sol<-nls(TOTAL~a*DBH^b,data=rd,start=list(a=0.01,b=2))中的可以rd$STEM, rd$TOTAL 等等不做修改，不知这样表达的是否清楚，谢谢你的帮助

y <- rd$SKIN
yhat <- fitted(nls.sol)

(resul <- CalFun(y, yhat))

高手呀，今天太感谢你了

你好，我用的是联立方程组：
如下
library( systemfit )
STEM.formula<-STEM~ a1*DBH^b1/( a1*DBH^b1+ a2*DBH^b2+
             a3*DBH^b3+ a4*DBH^b4+ a5*DBH^b5)* (a0*DBH^b0)
SKIN.formula<-SKIN~ a2*DBH^b2/( a1*DBH^b1+ a2*DBH^b2+
             a3*DBH^b3+ a4*DBH^b4+ a5*DBH^b5)* (a0*DBH^b0)
LEAF.formula<-LEAF~ a3*DBH^b3/( a1*DBH^b1+ a2*DBH^b2+
             a3*DBH^b3+ a4*DBH^b4+ a5*DBH^b5)* (a0*DBH^b0)
BRANCH.formula<-BRANCH~ a4*DBH^b4/( a1*DBH^b1+ a2*DBH^b2+
             a3*DBH^b3+ a4*DBH^b4+ a5*DBH^b5)* (a0*DBH^b0)
UNDER.formula<-UNDER~ a5*DBH^b5/( a1*DBH^b1+ a2*DBH^b2+
             a3*DBH^b3+ a4*DBH^b4+ a5*DBH^b5)* (a0*DBH^b0)
TOTAL.formula<-UNDER~ (a0*DBH^b0)^2/( a1*DBH^b1+ a2*DBH^b2+
             a3*DBH^b3+ a4*DBH^b4+ a5*DBH^b5)
labels <- list( " STEM.formula ", " SKIN.formula ", " LEAF.formula ", " BRANCH.formula ",
" UNDER.formula ",  " TOTAL.formula ")
inst <- ~ DBH+STEM+SKIN+LEAF+BRANCH+UNDERL+TOTAL
start.values <- c(a0=0.1,b0=2.3,a1=0.06,b1=2.4,a2=0.03,b2=1.8,a3=0.02,b3=1.7,
a4=0.05,b4=1.8,a5=0.01,b5=2.4)
model<-list(STEM.formula,SKIN.formula,LEAF.formula,BRANCH.formula,UNDER.formula, TOTAL.formula)
model.ols <- nlsystemfit( "OLS", model, start.values, data=rd, eqnlabels=labels )

用你给的方程求出
y <- rd$LEAF
hat <- fitted(LEAF.formula)
ErYuan (y, yhat)
R.Squred SEE TRE MSE MPE MPSE
  1               0   NaN   0    0     0
您能帮我找找原因吗？非常感谢