Hi r-users,
 
I have the following code to solve 4 simultaneous eqns with 4 unknowns using newton iteration method.  But I got the error message:
 
pars <- c(1.15, 40, 50, 0.78)
newton.input2 <- function(pars)
{  ## parameters to estimate
  
   alp <- pars[1] 
   b1  <- pars[2]  
   b2  <- pars[3]
   rho <- pars[4] 
 
f1 <- pars[1]*pars[2]
f2 <- pars[1]*(pars[1]+1)*pars[2]^2 
f3 <- pars[1]*(pars[1]+1)*pars[3]^2
f4 <- pars[1]*pars[2]*pars[3](pars[1]+pars[4]) 
fval  <- c(f1,f2,f3,f4)
## jacobian matrix
j11 <- pars[2]
j12 <- pars[1]
j13 <- 0
j14 <- 0
j21 <-  (2*pars[1]+1)*pars[2]^2
j22 <-  2*pars[2]*pars[1]*(pars[1]+1) 
j23 <-  0
j24 <-  0
j31 <- (2*pars[1]+1)*pars[3]^2
j32 <- 2*pars[3]*pars[1]*(pars[1]+1)
j33 <- 0
j34 <- 0
j41 <- pars[2]*pars[3]*(2*pars[1]+pars[4])
j42 <- pars[3]*(pars[3]^2+pars[3]*pars[4])
j43 <- pars[2]*(pars[3]^2+pars[3]*pars[4])
j44 <- pars[3]*pars[2]*pars[3]                            
jacobian <- matrix(c(j11,j12,j13,j14,j21,j22,j23,j24,j31,j32,j33,j34,j41,j42,j43,j44),byrow=TRUE,ncol=4)
## output
list(fval=fval,jacobian=jacobian)
}
newton.input2(pars)
newt(newton.input2, c(1,20,30,0.5))
 
Note: I use 'newt' code is develope by Rolf Turner.
 
Thank you.

 
Error message:
 
> newton.input2(pars)
Error in newton.input2(pars) : attempt to apply non-function
> newt(newton.input2, c(1,20,30,0.5))
Error in fn(p.o, ...) : attempt to apply non-function


      
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