How to get rid of output in nlsolve?

pdeffebach · June 25, 2021, 4:02pm

I’m struggling to avoid printing the result after an nlsolve call.

Results of Nonlinear Solver Algorithm
 * Algorithm: Trust-region with dogleg and autoscaling
 * Starting Point: [-2.9444389791664403, -2.197224577336219, 2.0, -0.2231435513142097]
 * Zero: [-0.8473798621728809, 4.661998387995021, 2.996397431516435, -2.9186666380101856]
 * Inf-norm of residuals: 0.000000
 * Iterations: 9
 * Convergence: true
   * |x - x'| < 0.0e+00: false
   * |f(x)| < 1.0e-08: true
 * Function Calls (f): 10
 * Jacobian Calls (df/dx): 9

I tried doing this

redirect_stdout(() -> nlsolve(f!, params_init_vec), devnull)

But that doesn’t redirect the summary output. It does, however, make debugging very hard. What IO is the summary from NLSolve sent to?

Sukera · June 25, 2021, 4:17pm

Should just be whatever IO is passed to show:

github.com

JuliaNLSolvers/NLsolve.jl/blob/219672802ed79b3d8ae13fdc83febce3bd0acd37/src/nlsolve/solver_state_results.jl#L87-L100


      
          function Base.show(io::IO, r::SolverResults)
              @printf io "Results of Nonlinear Solver Algorithm\n"
              @printf io " * Algorithm: %s\n" r.method
              @printf io " * Starting Point: %s\n" string(r.initial_x)
              @printf io " * Zero: %s\n" string(r.zero)
              @printf io " * Inf-norm of residuals: %f\n" r.residual_norm
              @printf io " * Iterations: %d\n" r.iterations
              @printf io " * Convergence: %s\n" converged(r)
              @printf io "   * |x - x'| < %.1e: %s\n" r.xtol r.x_converged
              @printf io "   * |f(x)| < %.1e: %s\n" r.ftol r.f_converged
              @printf io " * Function Calls (f): %d\n" r.f_calls
              @printf io " * Jacobian Calls (df/dx): %d" r.g_calls
              return
          end

pdeffebach · June 25, 2021, 4:26pm

That is obviously true.

But it doesn’t help me understand why redirect_stdout doesn’t affect the printing. I also can’t find where the show method is actually called in the nlsolve function.

Sukera · June 25, 2021, 4:28pm

Well - redirect_stdout just returns whatever the given function returns, so that’s why it’s probably being printed. The REPL just displays the value it was given, calling show:

julia> redirect_stdout(() -> 1, devnull)
1

Would explain why everything inside nlsolve is swallowed, but not the summary.

pdeffebach · June 25, 2021, 4:30pm

I apologize. I had a print call I hadn’t realized.

Sukera · June 25, 2021, 4:32pm

No need to apologize! We all make these kinds of silly mistakes sometimes