I tried following code:

```
matrix1 = array(NA, c(3,4))
matrix2 = array(NA, c(3,4))
myfn = function(mat1, mat2){
for(x in 1:4) {
mat1[2,x] = 5
mat2[2,x] = 6
}
cat("MATRICES INSIDE FUNCTION: \n")
print(mat1)
print(mat2)
}
myfn(matrix1,matrix2)
matrix1
matrix2
```

The value of matrices change in the function but the original matrices are not changing. How can I change original matrices from within a function?

You may try:

```
myfn <- function(mat1, mat2, Ncol, rowIndex) {
vars <- sapply(substitute(list(mat1, mat2)), deparse)[-1]
mat1[rowIndex, 1:Ncol] <- 5
mat2[rowIndex, 1:Ncol] <- 6
lst <- setNames(list(mat1, mat2), vars)
list2env(lst, envir = .GlobalEnv)
}
myfn(matrix1, matrix2, 4, 2)
#<environment: R_GlobalEnv>
matrix1
[,1] [,2] [,3] [,4]
[1,] NA NA NA NA
[2,] 5 5 5 5
[3,] NA NA NA NA
matrix2
[,1] [,2] [,3] [,4]
[1,] NA NA NA NA
[2,] 6 6 6 6
[3,] NA NA NA NA
```