Add cassert explicitly

Author: yuki-koyama

src/gaussian-process-regression.cpp

@@ -1,10 +1,11 @@
+#include <cassert>
 #include <iostream>
+#include <tuple>
 #include <mathtoolbox/constants.hpp>
 #include <mathtoolbox/gaussian-process-regression.hpp>
 #include <mathtoolbox/kernel-functions.hpp>
 #include <mathtoolbox/log-determinant.hpp>
 #include <mathtoolbox/numerical-optimization.hpp>
-#include <tuple>
 
 using Eigen::MatrixXd;
 using Eigen::VectorXd;

src/probability-distributions.cpp

@@ -1,3 +1,4 @@
+#include <cassert>
 #include <cmath>
 #include <mathtoolbox/constants.hpp>
 #include <mathtoolbox/probability-distributions.hpp>

src/rbf-interpolation.cpp

@@ -1,4 +1,5 @@
 #include <Eigen/LU>
+#include <cassert>
 #include <cmath>
 #include <mathtoolbox/rbf-interpolation.hpp>
 

src/som.cpp

@@ -1,3 +1,4 @@
+#include <cassert>
 #include <Eigen/SparseCore>
 #include <mathtoolbox/data-normalization.hpp>
 #include <mathtoolbox/som.hpp>