From 0262897d75c086130006d3e3336091bf68d9c3d7 Mon Sep 17 00:00:00 2001
From: Angelos Mantzaflaris <filiatra@gmail.com>
Date: Mon, 7 Dec 2015 11:43:29 +0100
Subject: [PATCH 1/2] const correctness

---
 exprtk.hpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/exprtk.hpp b/exprtk.hpp
index a9aba4a..4ed4859 100644
--- a/exprtk.hpp
+++ b/exprtk.hpp
@@ -32069,7 +32069,7 @@ namespace exprtk
    }
 
    template <typename T>
-   inline T derivative(expression<T>& e,
+   inline T derivative(const expression<T>& e,
                        T& x,
                        const T& h = T(0.00000001))
    {
@@ -32088,7 +32088,7 @@ namespace exprtk
    }
 
    template <typename T>
-   inline T second_derivative(expression<T>& e,
+   inline T second_derivative(const expression<T>& e,
                               T& x,
                               const T& h = T(0.00001))
    {

From 84956c57b9bfbb4b5dd06abb2c1f571199e783e1 Mon Sep 17 00:00:00 2001
From: Angelos Mantzaflaris <filiatra@gmail.com>
Date: Mon, 7 Dec 2015 15:27:27 +0100
Subject: [PATCH 2/2] more const correctness

---
 exprtk.hpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/exprtk.hpp b/exprtk.hpp
index 4ed4859..0517a91 100644
--- a/exprtk.hpp
+++ b/exprtk.hpp
@@ -32108,7 +32108,7 @@ namespace exprtk
    }
 
    template <typename T>
-   inline T third_derivative(expression<T>& e,
+   inline T third_derivative(const expression<T>& e,
                              T& x,
                              const T& h = T(0.0001))
    {
@@ -32127,7 +32127,7 @@ namespace exprtk
    }
 
    template <typename T>
-   inline T derivative(expression<T>& e,
+   inline T derivative(const expression<T>& e,
                        const std::string& variable_name,
                        const T& h = T(0.00000001))
    {
@@ -32154,7 +32154,7 @@ namespace exprtk
    }
 
    template <typename T>
-   inline T second_derivative(expression<T>& e,
+   inline T second_derivative(const expression<T>& e,
                               const std::string& variable_name,
                               const T& h = T(0.00001))
    {
@@ -32181,7 +32181,7 @@ namespace exprtk
    }
 
    template <typename T>
-   inline T third_derivative(expression<T>& e,
+   inline T third_derivative(const expression<T>& e,
                              const std::string& variable_name,
                              const T& h = T(0.0001))
    {