diff --git a/src/BTCSDiffusion.cpp b/src/BTCSDiffusion.cpp
index 870479c..ceef611 100644
--- a/src/BTCSDiffusion.cpp
+++ b/src/BTCSDiffusion.cpp
@@ -70,7 +70,8 @@ void BTCSDiffusion::updateInternals() {
   bc.resize(cells, {BTCSDiffusion::BC_CLOSED, 0});
 }
 
-void BTCSDiffusion::simulate1D(Eigen::Map<Eigen::VectorXd> &c, boundary_condition left,
+void BTCSDiffusion::simulate1D(Eigen::Map<Eigen::VectorXd> &c,
+                               boundary_condition left,
                                boundary_condition right,
                                const std::vector<double> &alpha, double dx,
                                int size) {
@@ -78,10 +79,10 @@ void BTCSDiffusion::simulate1D(Eigen::Map<Eigen::VectorXd> &c, boundary_conditio
   bool left_is_constant = (left.type == BTCSDiffusion::BC_CONSTANT);
   bool right_is_constant = (right.type == BTCSDiffusion::BC_CONSTANT);
 
-  //The sizes for matrix and vectors of the equation system is defined by the
-  //actual size of the input vector and if the system is (partially) closed.
-  //Then we will need ghost nodes. So this variable will give the count of ghost
-  //nodes.
+  // The sizes for matrix and vectors of the equation system is defined by the
+  // actual size of the input vector and if the system is (partially) closed.
+  // Then we will need ghost nodes. So this variable will give the count of
+  // ghost nodes.
   int bc_offset = !left_is_constant + !right_is_constant;
   ;
 
@@ -140,10 +141,8 @@ void BTCSDiffusion::simulate1D(Eigen::Map<Eigen::VectorXd> &c, boundary_conditio
 
   x_vector = solver.solve(b_vector);
 
-  //fill solution back in place into =c= vector
-  for (int i = 0, j = i + !left_is_constant; i < c.size(); i++, j++) {
-    c[i] = x_vector[i + !left_is_constant];
-  }
+  // write back result to input/output vector
+  c = x_vector.segment(!left_is_constant, c.size());
 }
 
 void BTCSDiffusion::setTimestep(double time_step) {