Technical facts

Operating system(s) or programming environment(s)

Lubuntu 15.04 (vivid)

IDE(s):

Qt Creator 3.1.1

Project type:

Console application

C++ standard:

C++98

Compiler(s):

G++ 4.9.2

Libraries used:

STL: GNU ISO C++ Library, version 4.9.2

Qt project file: ./CppBoostUblasMatrixExample3/CppBoostUblasMatrixExample3.pro


include(../../ConsoleApplication.pri) #Or use the code below

# QT += core

# QT += gui

# greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

# CONFIG   += console

# CONFIG   -= app_bundle

# TEMPLATE = app

# CONFIG(release, debug|release) {

#   DEFINES += NDEBUG NTRACE_BILDERBIKKEL

# }

# QMAKE_CXXFLAGS += -std=c++1y -Wall -Wextra -Weffc++

# unix {

#   QMAKE_CXXFLAGS += -Werror

# }



include(../../Libraries/Boost.pri) #Or use the code below

# win32 {

#   INCLUDEPATH += \

#     ../../Libraries/boost_1_54_0

# }



SOURCES += main.cpp

./CppBoostUblasMatrixExample3/main.cpp


#include <boost/numeric/ublas/matrix.hpp>



const boost::numeric::ublas::matrix<double> Inverse(

  const boost::numeric::ublas::matrix<double>& m)

{

  assert(m.size1() == m.size2() && "Can only calculate the inverse of square matrices");

  assert(m.size1() == 2 && m.size2() == 2 && "Only for 2x2 matrices");

  boost::numeric::ublas::matrix<double> n(2,2);

  const double a = m(0,0);

  const double b = m(0,1);

  const double c = m(1,0);

  const double d = m(1,1);

  assert((a * d) - (b * c) != 0.0 && "Determinant must be nonzero");

  const double determinant = 1.0 / ((a * d) - (b * c));

  n(0,0) =  d * determinant;

  n(0,1) = -b * determinant;

  n(1,0) = -c * determinant;

  n(1,1) =  a * determinant;

  return n;

}



const boost::numeric::ublas::matrix<double> CreateMatrix()

{

  boost::numeric::ublas::matrix<double> m(2,2); //y-x-ordered

  m(0,0) = 4.0;

  m(0,1) = 7.0;

  m(1,0) = 2.0;

  m(1,1) = 6.0;

  return m;

}



bool IsAboutEqual(const double x, const double y) { return std::abs(x-y) < 0.00001; }



int main()

{

  //Create an example matrix

  const boost::numeric::ublas::matrix<double> m = CreateMatrix();



  assert(IsAboutEqual(m(0,0),4.0)); assert(IsAboutEqual(m(0,1),7.0));

  assert(IsAboutEqual(m(1,0),2.0)); assert(IsAboutEqual(m(1,1),6.0));



  //Obtain the inverse of the example matrix

  const boost::numeric::ublas::matrix<double> n = Inverse(m);



  assert(IsAboutEqual(n(0,0), 0.6)); assert(IsAboutEqual(n(0,1),-0.7));

  assert(IsAboutEqual(n(1,0),-0.2)); assert(IsAboutEqual(n(1,1), 0.4));



  //Check that the product of a matrix and its inverse yields an identity matrix

  const boost::numeric::ublas::matrix<double> p = boost::numeric::ublas::prod(m,n);



  assert(IsAboutEqual(p(0,0),1.0)); assert(IsAboutEqual(p(0,1),0.0));

  assert(IsAboutEqual(p(1,0),0.0)); assert(IsAboutEqual(p(1,1),1.0));

}

Go back to Richel Bilderbeek's C++ page.

Go back to Richel Bilderbeek's homepage.

This page has been created by the tool CodeToHtml

(C++) BoostUblasMatrixExample3

Technical facts

Qt project file: ./CppBoostUblasMatrixExample3/CppBoostUblasMatrixExample3.pro

./CppBoostUblasMatrixExample3/main.cpp