PROGRAMA DE PÓS-GRADUAÇÃO EM ENGENHARIA CIVIL - PPGEC
CENTRO TECNOLÓGICO
UNIVERSIDADE FEDERAL DE SANTA CATARINA
Caixa Postal 476 - CEP 88010-970 - Florianópolis / SC - Fone (048) 3721.5175
e.mail : rafael.holdorf@ufsc.br home page: http://www.ecv.ufsc.br ; http://ppgec.posgrad.ufsc.br/
TUTORIAL
How to use the SGA code
This tutorial is a step by step explanation about how to use the SGA code. The sections and equations
cited below refer to the paper that presented the SGA:
M.S. Gonçalves, R.H. Lopez, L.F.F. Miguel, “Search group algorithm: A new metaheuristic method
for the optimization of truss structures”, Computers & Structures, 153:165-184, 2015.
0.1016/j.compstruc.2015.03.003
STEP 01
Define the problem to be solved in the file “fobjs.m”. In this file, the user must provide:
1) the objective function to be solved (fobj)
2) the number of design variables of the problem (dim)
3) the upper and lower bounds of the design domain (ub and lb, respectively): these must be column
vectors
STEP 02
1) AlfaMin: Initial value of alpha: Eq.(6)
2) AlfaInitial: Minimum value that alpha may assume in Eq.(6): see section 3.4
3) PopulationSize: Population size: npop of Eq.(4)
4) SearchGroupRatio: Ratio of PopulationSize that forms the search group (0.1 = 10%)
5) NIterations: Maximum number of iterations (it_max)
6) GlobalIterationsRatio: Ratio of iterations dedicated to global phase selection scheme: see section 3.5
7) NPerturbed: Number of mutated individuals of the search group: see Eq.(5) in section 3.3
8) PlotFamily: true to plot and false not to plot
STEP 03
Run the file “Example.m” and the results will be stored in the variables:
1) xopt: minimum found
2) fopt: objective function value at the minimum
Obs.: the algorithm will print the number of OFEs(Objective function evaluations) if a OFE counter if
placed inside the objective function as follows:
global OFEs
OFEs=OFEs+1;
IMPORTANT TIPS:
1) The ratio values (SearchGroupRatio, GlobalIterationsRatio) must be real values between 0 and 1,
noting that the size of the search group (round(SearchGroupRatio × PopulationSize)) must be greater
than zero.
2) In this version of the code, the following parameters are automatically assigned:
