diff --git a/ChangeLog b/ChangeLog
index 3314137..ae80078 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,7 @@
         * Version 1.3.0 released
         =========================
 
+        Add scalar addition and subtraction operators to matrix classes (#1990)
         Allow fitting of scale parameter in composite models (#1992)
         Add GCTAAeff::ebounds() method (#1989)
         Add GEbounds::emin() and GEbounds::emax() setter methods (#1989)
diff --git a/NEWS b/NEWS
index df13119..881d158 100644
--- a/NEWS
+++ b/NEWS
@@ -28,6 +28,18 @@ The following methods have been added:
 - GEbounds::emax(int&, GEnergy&)
 - GEnergies::set(GEbounds&)
 - GFilename::type()
+- GMatrix::operator+(double&)
+- GMatrix::operator-(double&)
+- GMatrix::operator+=(double&)
+- GMatrix::operator-=(double&)
+- GMatrixSymmetric::operator+(double&)
+- GMatrixSymmetric::operator-(double&)
+- GMatrixSymmetric::operator+=(double&)
+- GMatrixSymmetric::operator-=(double&)
+- GMatrixSparse::operator+(double&)
+- GMatrixSparse::operator-(double&)
+- GMatrixSparse::operator+=(double&)
+- GMatrixSparse::operator-=(double&)
 - GCTAResponseIrf::rspname()
 - GCTARoi::contains(GCTAInstDir&)
 - GCTAEdisp2D::fetch()
@@ -84,7 +96,8 @@ image of any type into a specific storage class (#1986).
 
 7. Linear algebra module
 ------------------------
-None
+Add operators for addition and subtraction of scalars to all matrix classes
+(#1990).
 
 
 8. Model module
diff --git a/include/GMatrix.hpp b/include/GMatrix.hpp
index 3939799..cab18b9 100644
--- a/include/GMatrix.hpp
+++ b/include/GMatrix.hpp
@@ -1,7 +1,7 @@
 /***************************************************************************
  *                      GMatrix.hpp - General matrix class                 *
  * ----------------------------------------------------------------------- *
- *  copyright (C) 2006-2014 by Juergen Knoedlseder                         *
+ *  copyright (C) 2006-2017 by Juergen Knoedlseder                         *
  * ----------------------------------------------------------------------- *
  *                                                                         *
  *  This program is free software: you can redistribute it and/or modify   *
@@ -96,11 +96,15 @@ public:
     virtual GMatrix&      operator=(const GMatrix& matrix);
     virtual GMatrix&      operator=(const double& value);
     virtual GMatrix       operator+(const GMatrix& matrix) const;
+    virtual GMatrix       operator+(const double& scalar) const;
     virtual GMatrix       operator-(const GMatrix& matrix) const;
+    virtual GMatrix       operator-(const double& scalar) const;
     virtual GMatrix       operator*(const GMatrix& matrix) const;
     virtual GMatrix       operator-(void) const;
     virtual GMatrix&      operator+=(const GMatrix& matrix);
+    virtual GMatrix&      operator+=(const double& scalar);
     virtual GMatrix&      operator-=(const GMatrix& matrix);
+    virtual GMatrix&      operator-=(const double& scalar);
     virtual GMatrix&      operator*=(const GMatrix& matrix);
     virtual GMatrix&      operator*=(const double& scalar);
     virtual GMatrix&      operator/=(const double& scalar);
@@ -207,6 +211,23 @@ GMatrix GMatrix::operator+(const GMatrix& matrix) const
 
 
 /***********************************************************************//**
+ * @brief Binary matrix scalar addition
+ *
+ * @param[in] scalar Scalar.
+ * @return Matrix with @p scalar added.
+ *
+ * Returns a matrix where a @p scalar has been added to each matrix element.
+ ***************************************************************************/
+inline
+GMatrix GMatrix::operator+(const double& scalar) const
+{
+    GMatrix result = *this;
+    result += scalar;
+    return result;
+}
+
+
+/***********************************************************************//**
  * @brief Binary matrix subtraction
  *
  * @param[in] matrix Matrix.
@@ -225,6 +246,24 @@ GMatrix GMatrix::operator-(const GMatrix& matrix) const
 
 
 /***********************************************************************//**
+ * @brief Binary matrix scalar subtraction
+ *
+ * @param[in] scalar Scalar.
+ * @return Matrix with @p scalar subtracted.
+ *
+ * Returns a matrix where a @p scalar has been subtracted from each matrix
+ * element.
+ ***************************************************************************/
+inline
+GMatrix GMatrix::operator-(const double& scalar) const
+{
+    GMatrix result = *this;
+    result -= scalar;
+    return result;
+}
+
+
+/***********************************************************************//**
  * @brief Binary matrix multiplication
  *
  * @param[in] matrix Matrix.
diff --git a/include/GMatrixSparse.hpp b/include/GMatrixSparse.hpp
index ddb0efa..8ce8ae7 100644
--- a/include/GMatrixSparse.hpp
+++ b/include/GMatrixSparse.hpp
@@ -1,7 +1,7 @@
 /***************************************************************************
  *                  GMatrixSparse.hpp - Sparse matrix class                *
  * ----------------------------------------------------------------------- *
- *  copyright (C) 2006-2014 by Juergen Knoedlseder                         *
+ *  copyright (C) 2006-2017 by Juergen Knoedlseder                         *
  * ----------------------------------------------------------------------- *
  *                                                                         *
  *  This program is free software: you can redistribute it and/or modify   *
@@ -221,11 +221,15 @@ public:
     virtual GMatrixSparse& operator=(const GMatrixSparse& matrix);
     virtual GMatrixSparse& operator=(const double& value);
     virtual GMatrixSparse  operator+(const GMatrixSparse& matrix) const;
+    virtual GMatrixSparse  operator+(const double& scalar) const;
     virtual GMatrixSparse  operator-(const GMatrixSparse& matrix) const;
+    virtual GMatrixSparse  operator-(const double& scalar) const;
     virtual GMatrixSparse  operator*(const GMatrixSparse& matrix) const;
     virtual GMatrixSparse  operator-(void) const;
     virtual GMatrixSparse& operator+=(const GMatrixSparse& matrix);
+    virtual GMatrixSparse& operator+=(const double& scalar);
     virtual GMatrixSparse& operator-=(const GMatrixSparse& matrix);
+    virtual GMatrixSparse& operator-=(const double& scalar);
     virtual GMatrixSparse& operator*=(const GMatrixSparse& matrix);
     virtual GMatrixSparse& operator*=(const double& scalar);
     virtual GMatrixSparse& operator/=(const double& scalar);
@@ -359,6 +363,23 @@ GMatrixSparse GMatrixSparse::operator+(const GMatrixSparse& matrix) const
 
 
 /***********************************************************************//**
+ * @brief Binary matrix scalar addition
+ *
+ * @param[in] scalar Scalar.
+ * @return Matrix with @p scalar added.
+ *
+ * Returns a matrix where a @p scalar has been added to each matrix element.
+ ***************************************************************************/
+inline
+GMatrixSparse GMatrixSparse::operator+(const double& scalar) const
+{
+    GMatrixSparse result = *this;
+    result += scalar;
+    return result;
+}
+
+
+/***********************************************************************//**
  * @brief Binary matrix subtraction
  *
  * @param[in] matrix Matrix.
@@ -377,6 +398,24 @@ GMatrixSparse GMatrixSparse::operator-(const GMatrixSparse& matrix) const
 
 
 /***********************************************************************//**
+ * @brief Binary matrix scalar subtraction
+ *
+ * @param[in] scalar Scalar.
+ * @return Matrix with @p scalar subtracted.
+ *
+ * Returns a matrix where a @p scalar has been subtracted from each matrix
+ * element.
+ ***************************************************************************/
+inline
+GMatrixSparse GMatrixSparse::operator-(const double& scalar) const
+{
+    GMatrixSparse result = *this;
+    result -= scalar;
+    return result;
+}
+
+
+/***********************************************************************//**
  * @brief Binary matrix multiplication
  *
  * @param[in] matrix Matrix.
diff --git a/include/GMatrixSymmetric.hpp b/include/GMatrixSymmetric.hpp
index 2a6ae83..4045216 100644
--- a/include/GMatrixSymmetric.hpp
+++ b/include/GMatrixSymmetric.hpp
@@ -1,7 +1,7 @@
 /***************************************************************************
  *                GMatrixSymmetric.hpp - Symmetric matrix class            *
  * ----------------------------------------------------------------------- *
- *  copyright (C) 2006-2014 by Juergen Knoedlseder                         *
+ *  copyright (C) 2006-2017 by Juergen Knoedlseder                         *
  * ----------------------------------------------------------------------- *
  *                                                                         *
  *  This program is free software: you can redistribute it and/or modify   *
@@ -88,11 +88,15 @@ public:
     virtual GMatrixSymmetric& operator=(const GMatrixSymmetric& matrix);
     virtual GMatrixSymmetric& operator=(const double& value);
     virtual GMatrixSymmetric  operator+(const GMatrixSymmetric& matrix) const;
+    virtual GMatrixSymmetric  operator+(const double& scalar) const;
     virtual GMatrixSymmetric  operator-(const GMatrixSymmetric& matrix) const;
+    virtual GMatrixSymmetric  operator-(const double& scalar) const;
     virtual GMatrix           operator*(const GMatrixSymmetric& matrix) const;
     virtual GMatrixSymmetric  operator-(void) const;
     virtual GMatrixSymmetric& operator+=(const GMatrixSymmetric& matrix);
+    virtual GMatrixSymmetric& operator+=(const double& scalar);
     virtual GMatrixSymmetric& operator-=(const GMatrixSymmetric& matrix);
+    virtual GMatrixSymmetric& operator-=(const double& scalar);
     virtual GMatrixSymmetric& operator*=(const double& scaler);
     virtual GMatrixSymmetric& operator/=(const double& scalar);
 
@@ -214,6 +218,23 @@ GMatrixSymmetric GMatrixSymmetric::operator+(const GMatrixSymmetric& matrix) con
 
 
 /***********************************************************************//**
+ * @brief Binary matrix scalar addition
+ *
+ * @param[in] scalar Scalar.
+ * @return Matrix with @p scalar added.
+ *
+ * Returns a matrix where a @p scalar has been added to each matrix element.
+ ***************************************************************************/
+inline
+GMatrixSymmetric GMatrixSymmetric::operator+(const double& scalar) const
+{
+    GMatrixSymmetric result = *this;
+    result += scalar;
+    return result;
+}
+
+
+/***********************************************************************//**
  * @brief Binary matrix subtraction
  *
  * @param[in] matrix Matrix.
@@ -232,6 +253,24 @@ GMatrixSymmetric GMatrixSymmetric::operator-(const GMatrixSymmetric& matrix) con
 
 
 /***********************************************************************//**
+ * @brief Binary matrix scalar subtraction
+ *
+ * @param[in] scalar Scalar.
+ * @return Matrix with @p scalar subtracted.
+ *
+ * Returns a matrix where a @p scalar has been subtracted from each matrix
+ * element.
+ ***************************************************************************/
+inline
+GMatrixSymmetric GMatrixSymmetric::operator-(const double& scalar) const
+{
+    GMatrixSymmetric result = *this;
+    result -= scalar;
+    return result;
+}
+
+
+/***********************************************************************//**
  * @brief Scale matrix elements
  *
  * @param[in] scalar Scale factor.
diff --git a/pyext/GMatrix.i b/pyext/GMatrix.i
index 89b2cc8..1e42701 100755
--- a/pyext/GMatrix.i
+++ b/pyext/GMatrix.i
@@ -1,7 +1,7 @@
 /***************************************************************************
  *                   GMatrix.i - General Matrix class                      *
  * ----------------------------------------------------------------------- *
- *  copyright (C) 2008-2016 by Juergen Knoedlseder                         *
+ *  copyright (C) 2008-2017 by Juergen Knoedlseder                         *
  * ----------------------------------------------------------------------- *
  *                                                                         *
  *  This program is free software: you can redistribute it and/or modify   *
@@ -53,8 +53,12 @@ public:
     virtual GMatrix       operator+(const GMatrix& matrix) const;
     virtual GMatrix       operator-(const GMatrix& matrix) const;
     virtual GMatrix       operator-(void) const;
+    virtual GMatrix       operator+(const double& scalar) const;
+    virtual GMatrix       operator-(const double& scalar) const;
     virtual GMatrix&      operator+=(const GMatrix& matrix);
+    virtual GMatrix&      operator+=(const double& scalar);
     virtual GMatrix&      operator-=(const GMatrix& matrix);
+    virtual GMatrix&      operator-=(const double& scalar);
     virtual GMatrix&      operator*=(const GMatrix& matrix);
     virtual GMatrix&      operator*=(const double& scalar);
 
diff --git a/pyext/GMatrixSparse.i b/pyext/GMatrixSparse.i
index 3bb0aa8..5ae9497 100644
--- a/pyext/GMatrixSparse.i
+++ b/pyext/GMatrixSparse.i
@@ -1,7 +1,7 @@
 /***************************************************************************
  *                   GMatrixSparse.i - Sparse matrix class                 *
  * ----------------------------------------------------------------------- *
- *  copyright (C) 2008-2016 by Juergen Knoedlseder                         *
+ *  copyright (C) 2008-2017 by Juergen Knoedlseder                         *
  * ----------------------------------------------------------------------- *
  *                                                                         *
  *  This program is free software: you can redistribute it and/or modify   *
@@ -55,10 +55,14 @@ public:
 
     // Other operators
     virtual GMatrixSparse  operator+(const GMatrixSparse& matrix) const;
+    virtual GMatrixSparse  operator+(const double& scalar) const;
     virtual GMatrixSparse  operator-(const GMatrixSparse& matrix) const;
+    virtual GMatrixSparse  operator-(const double& scalar) const;
     virtual GMatrixSparse  operator-(void) const;
     virtual GMatrixSparse& operator+=(const GMatrixSparse& matrix);
+    virtual GMatrixSparse& operator+=(const double& scalar);
     virtual GMatrixSparse& operator-=(const GMatrixSparse& matrix);
+    virtual GMatrixSparse& operator-=(const double& scalar);
     virtual GMatrixSparse& operator*=(const GMatrixSparse& matrix);
     virtual GMatrixSparse& operator*=(const double& scalar);
 
diff --git a/pyext/GMatrixSymmetric.i b/pyext/GMatrixSymmetric.i
index bdeb8de..83a6cdb 100644
--- a/pyext/GMatrixSymmetric.i
+++ b/pyext/GMatrixSymmetric.i
@@ -1,7 +1,7 @@
 /***************************************************************************
  *              GMatrixSymmetric.i - Symmetric matrix class                *
  * ----------------------------------------------------------------------- *
- *  copyright (C) 2008-2016 by Juergen Knoedlseder                         *
+ *  copyright (C) 2008-2017 by Juergen Knoedlseder                         *
  * ----------------------------------------------------------------------- *
  *                                                                         *
  *  This program is free software: you can redistribute it and/or modify   *
@@ -50,10 +50,14 @@ public:
 
     // Other operators
     virtual GMatrixSymmetric  operator+(const GMatrixSymmetric& matrix) const;
+    virtual GMatrixSymmetric  operator+(const double& scalar) const;
     virtual GMatrixSymmetric  operator-(const GMatrixSymmetric& matrix) const;
+    virtual GMatrixSymmetric  operator-(const double& scalar) const;
     virtual GMatrixSymmetric  operator-(void) const;
     virtual GMatrixSymmetric& operator+=(const GMatrixSymmetric& matrix);
+    virtual GMatrixSymmetric& operator+=(const double& scalar);
     virtual GMatrixSymmetric& operator-=(const GMatrixSymmetric& matrix);
+    virtual GMatrixSymmetric& operator-=(const double& scalar);
     virtual GMatrixSymmetric& operator*=(const double& scaler);
 
     // Implemented pure virtual base class methods
diff --git a/src/linalg/GMatrix.cpp b/src/linalg/GMatrix.cpp
index 7ccc856..f38874b 100644
--- a/src/linalg/GMatrix.cpp
+++ b/src/linalg/GMatrix.cpp
@@ -1,7 +1,7 @@
 /***************************************************************************
  *                    GMatrix.cpp - General matrix class                   *
  * ----------------------------------------------------------------------- *
- *  copyright (C) 2006-2013 by Juergen Knoedlseder                         *
+ *  copyright (C) 2006-2017 by Juergen Knoedlseder                         *
  * ----------------------------------------------------------------------- *
  *                                                                         *
  *  This program is free software: you can redistribute it and/or modify   *
@@ -362,6 +362,26 @@ GMatrix& GMatrix::operator+=(const GMatrix& matrix)
 
 
 /***********************************************************************//**
+ * @brief Unary matrix scalar addition operator
+ *
+ * @param[in] scaler Scalar.
+ *
+ * Adds a @p scalar to each matrix element.
+ ***************************************************************************/
+GMatrix& GMatrix::operator+=(const double& scalar)
+{
+    // Add all matrix elements
+    double* dst = m_data;
+    for (int i = 0; i < m_elements; ++i) {
+        *dst++ += scalar;
+    }
+
+    // Return result
+    return *this;
+}
+
+
+/***********************************************************************//**
  * @brief Unary matrix subtraction operator
  *
  * @param[in] matrix Matrix.
@@ -394,6 +414,26 @@ GMatrix& GMatrix::operator-=(const GMatrix& matrix)
 
 
 /***********************************************************************//**
+ * @brief Unary matrix scalar subtraction operator
+ *
+ * @param[in] scalar Scalar.
+ *
+ * Subtracts a @p scalar from each matrix element.
+ ***************************************************************************/
+GMatrix& GMatrix::operator-=(const double& scalar)
+{
+    // Add all matrix elements
+    double* dst = m_data;
+    for (int i = 0; i < m_elements; ++i) {
+        *dst++ -= scalar;
+    }
+
+    // Return result
+    return *this;
+}
+
+
+/***********************************************************************//**
  * @brief Unary matrix multiplication operator
  *
  * @param[in] matrix Matrix.
diff --git a/src/linalg/GMatrixSparse.cpp b/src/linalg/GMatrixSparse.cpp
index 888154b..fab598a 100644
--- a/src/linalg/GMatrixSparse.cpp
+++ b/src/linalg/GMatrixSparse.cpp
@@ -1,7 +1,7 @@
 /***************************************************************************
  *                   GMatrixSparse.cpp - Sparse matrix class               *
  * ----------------------------------------------------------------------- *
- *  copyright (C) 2006-2013 by Juergen Knoedlseder                         *
+ *  copyright (C) 2006-2017 by Juergen Knoedlseder                         *
  * ----------------------------------------------------------------------- *
  *                                                                         *
  *  This program is free software: you can redistribute it and/or modify   *
@@ -572,6 +572,27 @@ GMatrixSparse& GMatrixSparse::operator+=(const GMatrixSparse& matrix)
 
 
 /***********************************************************************//**
+ * @brief Unary matrix scalar addition operator
+ *
+ * @param[in] scaler Scalar.
+ *
+ * Adds a @p scalar to each matrix element.
+ ***************************************************************************/
+GMatrixSparse& GMatrixSparse::operator+=(const double& scalar)
+{
+    // Perform inplace matrix addition using vectors
+    for (int col = 0; col < m_cols; ++col) {
+        GVector vector = column(col);
+        vector += scalar;
+        column(col, vector);
+    }
+
+    // Return result
+    return *this;
+}
+
+
+/***********************************************************************//**
  * @brief Unary matrix subtraction operator
  *
  * @param[in] matrix Matrix.
@@ -607,6 +628,27 @@ GMatrixSparse& GMatrixSparse::operator-=(const GMatrixSparse& matrix)
 
 
 /***********************************************************************//**
+ * @brief Unary matrix scalar subtraction operator
+ *
+ * @param[in] scalar Scalar.
+ *
+ * Subtracts a @p scalar from each matrix element.
+ ***************************************************************************/
+GMatrixSparse& GMatrixSparse::operator-=(const double& scalar)
+{
+    // Perform inplace matrix subtraction
+    for (int col = 0; col < m_cols; ++col) {
+        GVector vector = column(col);
+        vector -= scalar;
+        column(col, vector);
+    }
+
+    // Return result
+    return *this;
+}
+
+
+/***********************************************************************//**
  * @brief Unary matrix multiplication operator
  *
  * @param[in] matrix Matrix.
diff --git a/src/linalg/GMatrixSymmetric.cpp b/src/linalg/GMatrixSymmetric.cpp
index 75c50bd..3d44722 100644
--- a/src/linalg/GMatrixSymmetric.cpp
+++ b/src/linalg/GMatrixSymmetric.cpp
@@ -1,7 +1,7 @@
 /***************************************************************************
  *                GMatrixSymmetric.cpp - Symmetric matrix class            *
  * ----------------------------------------------------------------------- *
- *  copyright (C) 2006-2013 by Juergen Knoedlseder                         *
+ *  copyright (C) 2006-2017 by Juergen Knoedlseder                         *
  * ----------------------------------------------------------------------- *
  *                                                                         *
  *  This program is free software: you can redistribute it and/or modify   *
@@ -412,6 +412,26 @@ GMatrixSymmetric& GMatrixSymmetric::operator+=(const GMatrixSymmetric& matrix)
 
 
 /***********************************************************************//**
+ * @brief Unary matrix scalar addition operator
+ *
+ * @param[in] scaler Scalar.
+ *
+ * Adds a @p scalar to each matrix element.
+ ***************************************************************************/
+GMatrixSymmetric& GMatrixSymmetric::operator+=(const double& scalar)
+{
+    // Add all matrix elements
+    double* dst = m_data;
+    for (int i = 0; i < m_elements; ++i) {
+        *dst++ += scalar;
+    }
+
+    // Return result
+    return *this;
+}
+
+
+/***********************************************************************//**
  * @brief Unary matrix subtraction operator
  *
  * @param[in] matrix Matrix.
@@ -443,6 +463,26 @@ GMatrixSymmetric& GMatrixSymmetric::operator-=(const GMatrixSymmetric& matrix)
 }
 
 
+/***********************************************************************//**
+ * @brief Unary matrix scalar subtraction operator
+ *
+ * @param[in] scalar Scalar.
+ *
+ * Subtracts a @p scalar from each matrix element.
+ ***************************************************************************/
+GMatrixSymmetric& GMatrixSymmetric::operator-=(const double& scalar)
+{
+    // Add all matrix elements
+    double* dst = m_data;
+    for (int i = 0; i < m_elements; ++i) {
+        *dst++ -= scalar;
+    }
+
+    // Return result
+    return *this;
+}
+
+
 /*==========================================================================
  =                                                                         =
  =                              Public methods                             =
diff --git a/test/Makefile.am b/test/Makefile.am
index eafa18e..32b3fb4 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -205,6 +205,7 @@ all-local:
 # Files to be removed in build directory
 clean-local:
 	rm -rf $(top_builddir)/test/*.fits
+	rm -rf $(top_builddir)/test/*.csv
 	rm -rf $(top_builddir)/test/*.log
 	rm -rf $(top_builddir)/test/*.html
 	rm -rf $(top_builddir)/test/*.xml
diff --git a/test/test_GMatrix.cpp b/test/test_GMatrix.cpp
index 31d7c90..f4ac07c 100644
--- a/test/test_GMatrix.cpp
+++ b/test/test_GMatrix.cpp
@@ -1,7 +1,7 @@
 /***************************************************************************
  *             test_GMatrix.cpp - Test generic matrix class                *
  * ----------------------------------------------------------------------- *
- *  copyright (C) 2006-2013 by Juergen Knoedlseder                         *
+ *  copyright (C) 2006-2017 by Juergen Knoedlseder                         *
  * ----------------------------------------------------------------------- *
  *                                                                         *
  *  This program is free software: you can redistribute it and/or modify   *
@@ -532,6 +532,32 @@ void TestGMatrix::matrix_arithmetics(void)
     test_assert(check_matrix(m_test), "Test source matrix");
     test_assert(check_matrix(test, 1.0/3.0, 0.0), "Test GMatrix / 3.0",
                 "Unexpected result matrix:\n"+test.print());
+   
+	// GMatrix + 3.0
+	test = m_test + 3.0;
+    test_assert(check_matrix(m_test), "Test source matrix");
+    test_assert(check_matrix(test, 1.0, 3.0), "Test GMatrix + 3.0",
+                "Unexpected result matrix:\n"+test.print());
+
+	// GMatrix += 3.0
+    test = m_test;
+    test += 3.0;
+    test_assert(check_matrix(m_test), "Test source matrix");
+    test_assert(check_matrix(test, 1.0, 3.0), "Test GMatrix + 3.0",
+                "Unexpected result matrix:\n"+test.print());
+    
+	// GMatrix - 5.0
+	test = m_test - 5.0;
+    test_assert(check_matrix(m_test), "Test source matrix");
+    test_assert(check_matrix(test, 1.0, -5.0), "Test GMatrix -= 5.0",
+                "Unexpected result matrix:\n"+test.print());
+
+	// GMatrix -= 3.0
+    test = m_test;
+    test -= 3.0;
+    test_assert(check_matrix(m_test), "Test source matrix");
+    test_assert(check_matrix(test, 1.0, -3.0), "Test GMatrix -= 3.0",
+                "Unexpected result matrix:\n"+test.print());
 
     // Test invalid matrix addition
     test_try("Test invalid matrix addition");
diff --git a/test/test_GMatrixSparse.cpp b/test/test_GMatrixSparse.cpp
index 178ca4b..2c55d53 100644
--- a/test/test_GMatrixSparse.cpp
+++ b/test/test_GMatrixSparse.cpp
@@ -1,7 +1,7 @@
 /***************************************************************************
  *            test_GMatrixSparse.cpp - Test sparse matrix class            *
  * ----------------------------------------------------------------------- *
- *  copyright (C) 2006-2016 by Juergen Knoedlseder                         *
+ *  copyright (C) 2006-2017 by Juergen Knoedlseder                         *
  * ----------------------------------------------------------------------- *
  *                                                                         *
  *  This program is free software: you can redistribute it and/or modify   *
@@ -861,6 +861,32 @@ void TestGMatrixSparse::matrix_arithmetics(void)
     test_assert(check_matrix(test, 1.0/3.0, 0.0), "Test GMatrixSparse / 3.0",
                 "Unexpected result matrix:\n"+test.print());
 
+	// GMatrixSparse + 3.0
+	test = m_test + 3.0;
+    test_assert(check_matrix(m_test), "Test source matrix");
+    test_assert(check_matrix(test, 1.0, 3.0), "Test GMatrixSparse + 3.0",
+                "Unexpected result matrix:\n"+test.print());
+
+	// GMatrixSparse += 3.0
+    test = m_test;
+    test += 3.0;
+    test_assert(check_matrix(m_test), "Test source matrix");
+    test_assert(check_matrix(test, 1.0, 3.0), "Test GMatrixSparse + 3.0",
+                "Unexpected result matrix:\n"+test.print());
+    
+	// GMatrixSparse - 5.0
+	test = m_test - 5.0;
+    test_assert(check_matrix(m_test), "Test source matrix");
+    test_assert(check_matrix(test, 1.0, -5.0), "Test GMatrixSparse -= 5.0",
+                "Unexpected result matrix:\n"+test.print());
+
+	// GMatrixSparse -= 3.0
+    test = m_test;
+    test -= 3.0;
+    test_assert(check_matrix(m_test), "Test source matrix");
+    test_assert(check_matrix(test, 1.0, -3.0), "Test GMatrixSparse -= 3.0",
+                "Unexpected result matrix:\n"+test.print());
+
     // Test invalid matrix addition
     test_try("Test invalid matrix addition");
     try {
diff --git a/test/test_GMatrixSymmetric.cpp b/test/test_GMatrixSymmetric.cpp
index db7fdd3..3c241a8 100644
--- a/test/test_GMatrixSymmetric.cpp
+++ b/test/test_GMatrixSymmetric.cpp
@@ -1,7 +1,7 @@
 /***************************************************************************
  *          test_GMatrixSymmetric.cpp - Test symmetric matrix class        *
  * ----------------------------------------------------------------------- *
- *  copyright (C) 2006-2013 by Juergen Knoedlseder                         *
+ *  copyright (C) 2006-2017 by Juergen Knoedlseder                         *
  * ----------------------------------------------------------------------- *
  *                                                                         *
  *  This program is free software: you can redistribute it and/or modify   *
@@ -537,6 +537,32 @@ void TestGMatrixSymmetric::matrix_arithmetics(void)
     test_assert(check_matrix(test, 1.0/3.0, 0.0), "Test GMatrixSymmetric / 3.0",
                 test.print());
 
+	// GMatrixSymmetric + 3.0
+	test = m_test + 3.0;
+    test_assert(check_matrix(m_test), "Test source matrix");
+    test_assert(check_matrix(test, 1.0, 3.0), "Test GMatrixSymmetric + 3.0",
+                "Unexpected result matrix:\n"+test.print());
+
+	// GMatrixSymmetric += 3.0
+    test = m_test;
+    test += 3.0;
+    test_assert(check_matrix(m_test), "Test source matrix");
+    test_assert(check_matrix(test, 1.0, 3.0), "Test GMatrixSymmetric + 3.0",
+                "Unexpected result matrix:\n"+test.print());
+    
+	// GMatrixSymmetric - 5.0
+	test = m_test - 5.0;
+    test_assert(check_matrix(m_test), "Test source matrix");
+    test_assert(check_matrix(test, 1.0, -5.0), "Test GMatrixSymmetric -= 5.0",
+                "Unexpected result matrix:\n"+test.print());
+
+	// GMatrixSymmetric -= 3.0
+    test = m_test;
+    test -= 3.0;
+    test_assert(check_matrix(m_test), "Test source matrix");
+    test_assert(check_matrix(test, 1.0, -3.0), "Test GMatrixSymmetric -= 3.0",
+                "Unexpected result matrix:\n"+test.print());
+
     // Test invalid matrix addition
     test_try("Test invalid matrix addition");
     try {