Filter Content By
Version

### mip2.m

function mip2(filename)

% Copyright 2020, Gurobi Optimization, LLC
%
% This example reads a MIP model from a file, solves it and prints
% the objective values from all feasible solutions generated while
% solving the MIP. Then it creates the associated fixed model and
% solves that model.

cols = size(model.A, 2);

ivars = find(model.vtype ~= 'C');
ints = length(ivars);

if ints <= 0
fprintf('All variables of the model are continuous, nothing to do\n');
return;
end

% Optimize
params.poolsolutions = 20;
result = gurobi(model, params);

% Capture solution information
if ~strcmp(result.status, 'OPTIMAL')
fprintf('This model cannot be solved because its optimization status is %s\n', ...
result.status);
return;
end

% Iterate over the solutions
if isfield(result, 'pool') && ~isempty(result.pool)
solcount = length(result.pool);
for k = 1:solcount
fprintf('Solution %d has objective %g\n', k, result.pool(k).objval);
end
else
fprintf('Solution 1 has objective %g\n', result.objval);
end

% Convert to fixed model
for j = 1:cols
if model.vtype(j) ~= 'C'
t = floor(result.x(j) + 0.5);
model.lb(j) = t;
model.ub(j) = t;
end
end

% Solve the fixed model
result2 = gurobi(model, params);
if ~strcmp(result.status, 'OPTIMAL')
fprintf('Error: fixed model is not optimal\n');
return;
end
if abs(result.objval - result2.objval) > 1e-6 * (1 + abs(result.objval))
fprintf('Error: Objective values differ\n');
end

% Print values of non-zero variables
for j = 1:cols
if abs(result2.x(j)) > 1e-6
fprintf('%s %g\n', model.varnames{j}, result2.x(j));
end
end


Choose the evaluation license that fits you best, and start working with our Expert Team for technical guidance and support.

Get a free, full-featured license of the Gurobi Optimizer to experience the performance, support, benchmarking and tuning services we provide as part of our product offering.
Gurobi supports the teaching and use of optimization within academic institutions. We offer free, full-featured copies of Gurobi for use in class, and for research.
##### Cloud Trial

Request free trial hours, so you can see how quickly and easily a model can be solved on the cloud.