**caRamel** is a multiobjective evolutionary algorithm combining the MEAS algorithm and the NGSA-II algorithm.

Download the package from CRAN or GitHub and then install and load it.

`library(caRamel)`

There are three possible choices on how **caRamel** can call the R user functions. Each choice is parameterized by the *carallel* value.

The computation of the user functions can be done sequentially or in parallel for each individual of the genetic population according to the choice of *carallel* when calling **caRamel**.

The evaluation of the population is done in a sequential mode if *carallel* is 0, or in parallel if *carallel* is 1 (this last one is the default option).

For these two options, the R user function takes a single input parameter *i* giving the number of the individual of the population *x*. For instance:

```
kursawe <- function(i) {
k1 <- -10 * exp(-0.2 * sqrt(x[i,1] ^ 2 + x[i,2] ^ 2)) - 10 * exp(-0.2 * sqrt(x[i,2] ^2 + x[i,3] ^ 2))
k2 <- abs(x[i,1]) ^ 0.8 + 5 * sin(x[i,1] ^ 3) + abs(x[i,2]) ^ 0.8 + 5 * sin(x[i,2] ^3) + abs(x[i,3]) ^ 0.8 + 5 * sin(x[i,3] ^ 3)
return(c(k1, k2))
}
```

Two objectives are evaluated here and a vector of the corresponding values is returned for the individual *x[i,]*.

If the value of *carallel* is 2 then the entire population is given to the R user function and one has to decide how to evaluate it. For instance hereafter with a simple for-loop:

```
kursawe <- function(x) { # receipt of the entire population
popsize <- dim(x)[1] # size of the population to evaluate
nobj <- 2 # number of objectives
results <- matrix(0, nrow = popsize, ncol = nobj) # matrix of results
for(i in 1:popsize){
k1 <- -10 * exp(-0.2 * sqrt(x[i,1] ^ 2 + x[i,2] ^ 2)) - 10 * exp(-0.2 * sqrt(x[i,2] ^2 + x[i,3] ^ 2))
k2 <- abs(x[i,1]) ^ 0.8 + 5 * sin(x[i,1] ^ 3) + abs(x[i,2]) ^ 0.8 + 5 * sin(x[i,2] ^3) + abs(x[i,3]) ^ 0.8 + 5 * sin(x[i,3] ^ 3)
results[i,] <- c(k1, k2)
}
return(results)
}
```