# Performs multi objective machine coded genetic algorithms.

### Description

Machine coded genetic algorithm (MCGA) is a fast tool for real-valued optimization problems. It uses the byte representation of variables rather than real-values. It performs the classical crossover operations (uniform) on these byte representations. Mutation operator is also similar to classical mutation operator, which is to say, it changes a randomly selected byte value of a chromosome by +1 or -1 with probability 1/2. In MCGAs there is no need for encoding-decoding process and the classical operators are directly applicable on real-values. It is fast and can handle a wide range of a search space with high precision. Using a 256-unary alphabet is the main disadvantage of this algorithm but a moderate size population is convenient for many problems.

This function performs multi objective optimization using the same logic underlying the mcga. Chromosomes are sorted by their objective values using a non-dominated sorting algorithm.

### Usage

1 2 | ```
multi_mcga(popsize, chsize, crossprob = 1.0, mutateprob = 0.01,
elitism = 1, minval, maxval, maxiter = 10, numfunc, evalFunc)
``` |

### Arguments

`popsize` |
Number of chromosomes. |

`chsize` |
Number of parameters. |

`crossprob` |
Crossover probability. By default it is 1.0 |

`mutateprob` |
Mutation probability. By default it is 0.01 |

`elitism` |
Number of best chromosomes to be copied directly into next generation. By default it is 1 |

`minval` |
The lower bound of the randomized initial population. This is not a constraint for parameters. |

`maxval` |
The upper bound of the randomized initial population. This is not a constraint for parameters. |

`maxiter` |
The maximum number of generations. By default it is 10. |

`numfunc` |
Number of objective functions. |

`evalFunc` |
An R function. By default, each problem is a minimization. This function must return a cost vector with dimension of numfunc. Each element of this vector points to the corresponding function to optimize. |

### Value

`population` |
Sorted population resulted after generations |

`costs` |
Cost values for each chromosomes in the resulted population |

`ranks` |
Calculated ranks using a non-dominated sorting for each chromosome |

### Author(s)

Mehmet Hakan Satman - mhsatman@istanbul.edu.tr

### References

Deb, K. (2000). An efficient constraint handling method for genetic algorithms. Computer methods in applied mechanics and engineering, 186(2), 311-338.

### Examples

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | ```
## Not run:
# We have two objective functions.
f1<-function(x){
return(sin(x))
}
f2<-function(x){
return(sin(2*x))
}
# This function returns a vector of cost functions for a given x sent from mcga
f<-function(x){
return ( c( f1(x), f2(x)) )
}
# main loop
m<-multi_mcga(popsize=200, chsize=1, minval= 0, elitism=2,
maxval= 2.0 * pi, maxiter=1000, crossprob=1.0,
mutateprob=0.01, evalFunc=f, numfunc=2)
# Points show best five solutions.
curve(f1, 0, 2*pi)
curve(f2, 0, 2*pi, add=TRUE)
p <- m$population[1:5,]
points(p, f1(p))
points(p, f2(p))
## End(Not run)
``` |

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