Hi..
  
      i have an expression of the form:
  
  model1<-nls(y~beta1*(x1+(k1*x2)+(k1*k1*x3)+(k2*x4)+(k2*k1*x5)+(k2*k2*x6)+(k3*x7)+(k3*k4*x8)+(k3*k2*x9)+(k3*k3*x10)+          (k4*x11)+(k4*k1*x12)+(k4*k2*x13)+(k4*k3*x14)+(k4*k4*x15)+(k5*x16)+(k5*k1*x17)+(k5*k2*x18)+(k5*k3*x19)+             (k5*k4*x20)+(k5*k5*x21)+(k6*x22)+(k6*k1*x23)+(k6*k2*x24)+(k6*k3*x25)+(k6*k4*x26)+(k6*k5*x27)+(k6*k6*x28)+             (k7*x29)+(k7*k1*x30)+(k7*k2*x31)+(k7*k3*x32)+(k7*k4*x33)+(k7*k5*x34)+(k7*k6*x35)+(k7*k7*x36)),x,             start=c(beta1=-0.001480981,k1=0.001,k2=0.001,k3=0.001,k4=0.001,k5=0.001,k6=0.001,k7=0.001),control=c(maxiter=100))
  
  where beta1, k1 -- k7 are the parameters to be estimated and 
  x1---x36 are the columns of the dataframe x 
  
  when i run this expression I get the error 
  
  Error in eval(expr, envir, enclos) : numeric 'envir' arg not of length one
  
  I searched  a couple of previous posting on this error but none of them addressed it in detail
  
  Thanks
  
  Harsh
  
  
  
		
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