In parameter optimization the goal is to find a set of parameter values that maximize (or minimize) a complex multidimensional function. Sometimes minimizing a function makes more sense. To minimize a function, just multiply the function by minus one and then maximize. In this section we will see how the multigenic chromosomes of gene expression programming can be used to seek the maximum (or minimum) of a multidimensional function. For this kind of problem, each gene of a multigenic chromosome is used to discover the values of the different parameters in a function optimization task.