R Under development (unstable) (2023-11-25 r85635 ucrt) -- "Unsuffered Consequences"
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> 
> library(nleqslv)
> 
> # Brown almost linear function
> 
> brown <- function(x) {
+   	n <- length(x)
+ 	y <- numeric(n)
+ 
+   	y[1:(n-1)] <- x[1:(n-1)] + sum(x[1:n]) - (n + 1)
+   	y[n] <- prod(x[1:n]) - 1.0
+ 
+ 	y
+ }
> 
> brownjac <- function(x) {
+     n <- length(x)
+     J <- matrix(1,nrow=n,ncol=n)
+     diag(J) <- 2
+ 	xprod <- prod(x)
+     J[n,] <- xprod/x  # exact
+     J
+ }
> 
> print.result <- function(z, do.print.xf=FALSE) {
+     if( do.print.xf ) {
+         print(z$x)
+         print(z$fvec)
+     }
+     print(z$message)
+     print(all(abs(z$fvec)<=1e-8))
+ }
> 
> for( m in c("Newton","Broyden") ) {
+     for( n in c(50,100) ) {
+         xstart <- rep(1,n)/2
+         z <- nleqslv(xstart, brown, brownjac, method="Newton",
+                         control=list(trace=0,ftol=1e-10,delta="cauchy",allowSingular=TRUE))
+         print.result(z)
+     }
+ }
[1] "Function criterion near zero"
[1] TRUE
[1] "Function criterion near zero"
[1] TRUE
[1] "Function criterion near zero"
[1] TRUE
[1] "Function criterion near zero"
[1] TRUE
> 
> proc.time()
   user  system elapsed 
   0.14    0.06    0.20