**Table 2:** Parameter setting.

Parameter |
Definitions |
Values |

P | Population size | 20 |

f_{min} |
Minimum frequency | 0 |

f_{max} |
Maximum frequency | 5 |

A_{0} |
The initial loudness | 1 |

r_{0} |
The initial pulse rate | 0.5 |

α |
The loudness constant | 0.9 |

γ |
The rate of pulse emission constant | 0.9 |

ε |
Step size for checking for decent directions | 10^{-3} |

m |
Local PS repetition number | 5 |

∆_{0} |
Initial mesh size | (U)/3_{i} - L_{i} |

σ |
Reduction factor of mesh size | 0.01 |

m |
Local PS repetition number | 5 |

Max_{itr} |
Maximum iterations number | 2 d |

N_{elite} |
Number of best solution for final intensification | 1 |