Implemented a polynomiale mutation for a Population

src/ibea/mutation.cpp

-#include "population.h"
+#include "coco/coco.h"
 #include "mutation.h"
 
-Population polynomiale_mutation(Population pop){
+double polynomiale_mutation(double parent, const double eta,
+  const double lower_bound, const double upper_bound, coco_random_state_t *random_generator){
+
+  double child;
+  double u = coco_random_uniform(random_generator);
+  double delta = min((parent - lower_bound)/(upper_bound - lower_bound),
+                     (upper_bound - parent)/(upper_bound - lower_bound));
+  double delta_q;
+
+  if (u <= 0.5){
+    delta_q = ((2*u) + (1-2*u)*(1-delta)**(eta+1))**(1/(1+eta)) - 1;
+  }
+  else {
+    delta_q = 1 - (2*(1-u) + 2*(u-0.5)*(1-delta)**(eta+1))**(1/(1+eta));
+  }
+
+  child = parent + delta_q*(upper_bounds - lower_bounds);
+  return child;
+}
+
+void mutate(Population population, const double *lower_bounds, const double *upper_bounds,
+  const double eta, coco_random_state_t *random_generator){
+
+  double lb, up, u;
+  double size = population.getSizeMax();
+  double dimension = population.getDim();
+
+  for (int i; i<size; i++){
+    for (int j; j<dimension; j++){
+      lb = lower_bounds[j];
+      ub = upper_bounds[j];
+      u = coco_random_uniform(random_generator);
+      if (u <= 0.01){
+        population.setIndiv(i,j,polynomiale_mutation(population.get(i,j), eta, lb, up, random_generator))
+      }
+    }
+  }
 
-  return pop;
 }

src/ibea/mutation.h

 #ifndef MUTATION_H
 #define MUTATION_H
 
-Population polynomiale_mutation(Population pop);
+double polynomiale_mutation(double parent, const double eta,
+  const double lower_bound, const double upper_bound, coco_random_state_t *random_generator);
+
+void mutate(Population population, const double *lower_bounds, const double *upper_bounds,
+  const double eta, coco_random_state_t *random_generator);
 
 #endif