Q: I'm using a solver that supports warm-starts for integer problems. How do I communicate the initial solution to the solver?
A: You can use the setvalue function on a variable to set its initial value, e.g.
@variable(m, x[1:3], Int)
setvalue(x[1], 10.0)
setvalue(x[3], 2.0)If you don't set the value of a variable, the behavior is solver-dependent. Some solvers attempt to "complete" solutions that aren't completely specified.
Q: How can I suppress output in a solver-independent way?
A: JuMP does not currently support generic parameters independent of the chosen solver object. To suppress output with Gurobi, for example, one would say
m = Model(solver=GurobiSolver(OutputFlag=0))When a solver is not specified, i.e., the model is created with m = Model(), there's no option to suppress output. A workaround is to redirect STDOUT before and after the call to solve(m):
TT = STDOUT # save original STDOUT stream
redirect_stdout()
solve(m)
redirect_stdout(TT) # restore STDOUT