How to do sensitivity analysis in gamside? Give an example code and explain step by step.

model rec1_3 /all/; FILE OPT Cplex option file/cplex.opt/; PUT OPT; PUT'objrng all'/ 'rhsrng all'/; PUTCLOSE OPT; rec1_3.optfile=1; rec1_3.dictfile=4; option iterlim =100000000; option reslim=100000000; solve rec1_3 using LP minimizing z; display X.L,z.L;

! please be as above !