extension to the add_sample function and the Kernel object

src/limbo/model/gp.hpp

@@ -83,8 +83,10 @@ namespace limbo {
                 assert(observations.size() != 0);
                 assert(samples.size() == observations.size());
 
-                _dim_in = samples[0].size();
-                _kernel_function = KernelFunction(_dim_in); // the cost of building a functor should be relatively low
+		if (_dim_in != samples[0].size()) {
+		    _dim_in = samples[0].size();
+		    _kernel_function = KernelFunction(_dim_in); // the cost of building a functor should be relatively low
+		}
 
                 if (_dim_out != observations[0].size()) {
                     _dim_out = observations[0].size();
@@ -117,11 +119,14 @@ namespace limbo {
             void add_sample(const Eigen::VectorXd& sample, const Eigen::VectorXd& observation, double noise)
             {
                 if (_samples.empty()) {
+		  if (_dim_in != sample.size()) {
                     _dim_in = sample.size();
                     _kernel_function = KernelFunction(_dim_in); // the cost of building a functor should be relatively low
-
-                    _dim_out = observation.size();
-                    _mean_function = MeanFunction(_dim_out); // the cost of building a functor should be relatively low
+		  }
+		  if (_dim_out != observation.size()) {
+		    _dim_out = observation.size();
+		    _mean_function = MeanFunction(_dim_out); // the cost of building a functor should be relatively low
+		  }
                 }
                 else {
                     assert(sample.size() == _dim_in);