Correct gnm_solve to execute callback when equilibria are found her than waiting until the end of the run.

ChangeLog

@@ -3,6 +3,8 @@
 ### Changed
 - `lcp_solve` no longer silently absorbs internal exceptions if they occur, but instead these propagate out
   to match the behaviour of all other Nash equilibrium solvers.  (#996)
+- `gnm_solve` executes callback when equilibrium is found rather than emitting all equilibria at the end of
+  the run.  (#998)
 - Implemented bespoke XML parser that handles the subset in the de-facto legacy XML workbook .gbt format;
   removes dependency on tinyxml.  (#897)
 

src/solvers/gnm/gnm.cc

@@ -58,9 +58,8 @@ Solve(const Game &p_game, const std::shared_ptr<gnmgame> &p_rep, const cvector &
   };
   GNM(*p_rep, norm_pert, answers, p_steps, FUZZ, p_localNewtonInterval, p_localNewtonMaxits,
       p_lambdaEnd, WOBBLE, THRESHOLD, callback, return_message);
-  for (auto answer : answers) {
+  for (const auto &answer : answers) {
     eqa.push_back(ToProfile(p_game, answer));
-    p_callback(eqa.back(), "NE");
   }
   return eqa;
 }

src/solvers/gtracer/gnm.cc

@@ -326,7 +326,7 @@ void GNM(gnmgame &A, cvector &g, std::list<cvector> &Eq, int steps, double fuzz,
           if (ee < fuzz) { // only save high quality equilibria;
             // this restriction could be removed.
             Eq.push_back(sigma);
-            // PrintProfile(std::cout, "NE", sigma);
+            p_onStep("NE", Eq.back());
           }
           Index = -Index;
           s_hat_old = -1;

src/solvers/gtracer/gtracer.h

@@ -55,7 +55,8 @@ namespace Gambit::gametracer {
 /// @param threshold  the equilibrium error threshold for doing a wobble.  If
 ///                   wobbles are disabled, GNM will terminate if the error
 ///                   reaches this threshold.
-/// @param p_onStep   a callback function executed on each step of the algorithm
+/// @param p_onStep   a callback function executed on each step of the algorithm and whenever an
+///                   equilibrium is found (with label "NE")
 void GNM(gnmgame &A, cvector &g, std::list<cvector> &Eq, int steps, double fuzz, int LNMFreq,
          int LNMMax, double LambdaMin, bool wobble, double threshold,
          std::function<void(const std::string &, const cvector &)> p_onStep,