1 files changed, 15 insertions, 1 deletions
diff --git a/utils/chi2 b/utils/chi2
index 12b602a..0326e1a 100755
--- a/utils/chi2
+++ b/utils/chi2
@@ -35,6 +35,7 @@ from sddm.dc import estimate_errors, EPSILON, truncnorm_scaled
 import emcee
 from sddm import printoptions
 from sddm.utils import fast_cdf, correct_energy_bias
+import nlopt
 
 # Likelihood Fit Parameters
 # 0 - Atmospheric Neutrino Flux Scale
@@ -390,7 +391,20 @@ def do_fit(data,muon,data_mc,atmo_scale_factor,muon_scale_factor,bins,steps,prin
 
     samples = sampler.get_chain(flat=True,thin=thin)
 
-    return sampler.get_chain(flat=True)[sampler.get_log_prob(flat=True).argmax()], samples
+    # Now, we use nlopt to find the best set of parameters. We start at the
+    # best starting point from the MCMC and then run the SBPLX routine.
+    x0 = sampler.get_chain(flat=True)[sampler.get_log_prob(flat=True).argmax()]
+    opt = nlopt.opt(nlopt.LN_SBPLX, len(x0))
+    opt.set_min_objective(nll)
+    low = np.array(PRIORS_LOW)
+    high = np.array(PRIORS_HIGH)
+    opt.set_lower_bounds(low)
+    opt.set_upper_bounds(high)
+    opt.set_ftol_abs(1e-10)
+    opt.set_initial_step([0.01]*len(x0))
+    xopt = opt.optimize(x0)
+
+    return xopt, samples
 
 if __name__ == '__main__':
     import argparse