How can I run this parfor loop?

I want to use parfor loop. But, temporary variables error occurred. How can I fix that code?

• error variables are "old_pop", "old_fit", "old_obj"

% Input Data of Structural / (Import of Measured Displacement)
[NODE, ELEMENT, MATERIAL, SECTION, CONSTRAINT, SPRING, CONLOAD, displ_m] = ...
    InputStructureData('InputStructureData2ndLC2.txt');

% (Generation of Initial Population, ramdomly)
old_pop = generation(pop_size, total_chrom_length, range_vars, digit_number);

% (Evaluation of the Fitness)
[old_obj, old_fit] = fitness(old_pop, pop_size, optimization_method, ...
    penalty_coeff, displ_m, 1, NODE, ELEMENT, MATERIAL, SECTION, ...
    CONSTRAINT, CONLOAD, SPRING);

parfor n = 1:max_generation

      % (Selection)
      cross_pool = selection( old_pop, old_fit, pop_size, ...
          total_chrom_length, range_vars, selection_operator);

      % (Crossover)
      mutation_pool = crossover(cross_pool, pop_size, total_chrom_length, ...
          range_vars, crossover_prob, max_generation, step_mg, n);

      % (Mutation)
      elite_pool = mutation(mutation_pool, pop_size, total_chrom_length, ...
          range_vars, mutation_prob, max_generation, digit_number, step_mg, n);

      % (Evaluation of the Fitness)
      [new_obj, new_fit] = fitness(elite_pool, pop_size, ...
          optimization_method, penalty_coeff, displ_m, n, ...
          NODE, ELEMENT, MATERIAL, SECTION, CONSTRAINT, CONLOAD, SPRING);

      % (Elitism)
      [new_pop, new_obj, new_fit] = elite(old_pop, old_obj, old_fit, ...
          elite_pool, new_obj, new_fit);

      % (Print of the Result)
      [Result(n,:), old_pop, old_obj, old_fit] = ...
          result(new_pop, new_obj, new_fit);

      waitbar(n/max_generation, progress, ...
          sprintf('%d / %d Gen. (%.2f%%)  Complete', n,...
              max_generation, n/max_generation*100))

end

Answer 1

[Edric Ellis]

One of the primary requirements of a parfor loop is that the iterations must be order independent.

In this case, iteration i of your parfor loop is trying to use the values of old_pop and old_obj from iteration i-1. This is not allowed. To use parfor, you need to restructure your code so that the loop iterations are independent - this might not be possible in this case (there's no obvious easy way to do it that I can see).