diff --git a/Makefile b/Makefile
index aa37d1c..ee86b7e 100644
--- a/Makefile
+++ b/Makefile
@@ -45,13 +45,14 @@ shared: $(OBJ_SHARED)
 	$(CC) -shared -o libztd.so $^
 
 install: all
-	mv libztd.a libztd.so /usr/lib
-	mkdir -p /usr/include/ztd
-	cp -r include/* /usr/include/ztd
+	mkdir -p $(INSTALL)/usr/lib
+	mv libztd.a libztd.so $(INSTALL)/usr/lib
+	mkdir -p $(INSTALL)/usr/include/ztd
+	cp -r include/* $(INSTALL)/usr/include/ztd
 
 uninstall:
-	rm /usr/lib/libztd.*
-	rm -rd /usr/include/ztd
+	rm $(INSTALL)/usr/lib/libztd.*
+	rm -rd $(INSTALL)/usr/include/ztd
 
 clean:
 	rm $(ODIR)/*.o $(ODIR_SHARED)/*.o
diff --git a/include/complex.hpp b/include/complex.hpp
new file mode 100644
index 0000000..8771583
--- /dev/null
+++ b/include/complex.hpp
@@ -0,0 +1,54 @@
+#ifndef COMPLEX_HPP
+#define COMPLEX_HPP
+
+#include <iostream>
+
+/*! @file complex.hpp
+*  @brief Complex numbers and related computation
+*/
+
+namespace ztd
+{
+  //! @brief Complex number
+  class complex
+  {
+  public:
+    //! @brief Contructor a+bi
+    complex(const double& a=0, const double& b=0);
+    //! @brief Contructor z
+    complex(const complex& z);
+
+    //! @brief Complex Addition
+    complex& operator+=(const complex& z);
+    //! @brief Complex Substraction
+    complex& operator-=(const complex& z);
+    //! @brief Complex Multiplication
+    complex& operator*=(const complex& z);
+    //! @brief Complex Division
+    complex& operator/=(const complex& z);
+
+    //! @brief Real part
+    double real;
+    //! @brief Imaginary part
+    double im;
+
+  };
+
+  //! @brief Complex Addition
+  inline complex operator+(const complex& z1, const complex& z2) { complex z3(z1); return z3 += z1; }
+  //! @brief Complex Substraction
+  inline complex operator-(const complex& z1, const complex& z2) { complex z3(z1); return z3 -= z1; }
+  //! @brief Complex Multiplication
+  inline complex operator*(const complex& z1, const complex& z2) { complex z3(z1); return z3 *= z1; }
+  //! @brief Complex Division
+  inline complex operator/(const complex& z1, const complex& z2) { complex z3(z1); return z3 /= z1; }
+
+  //! @brief Output a+bi
+  inline std::ostream& operator<<(std::ostream& stream, complex z) { stream << z.real << '+' << z.im << 'i'; return stream; }
+
+  //! @brief Constant i definition
+  extern const complex i;
+
+}
+
+#endif //COMPLEX_HPP
diff --git a/include/options.hpp b/include/options.hpp
index b27fae3..12351e6 100644
--- a/include/options.hpp
+++ b/include/options.hpp
@@ -122,6 +122,7 @@ namespace ztd
     option* find(char c);
     //! @brief Find string option
     option* find(std::string const& str);
+    inline option* find(const char* str) { return this->find(std::string(str)); }
 
     /*PROCESSING FUNCTIONS*/
     //! @brief Process arguments through the option set
diff --git a/include/thread.hpp b/include/thread.hpp
deleted file mode 100644
index 58b31c9..0000000
--- a/include/thread.hpp
+++ /dev/null
@@ -1,40 +0,0 @@
-#ifndef THREAD_HPP
-#define THREAD_HPP
-
-#include <vector>
-#include <thread>
-
-/*! \file thread.hpp
-*  @brief Thread management
-*/
-
-namespace ztd
-{
-  //! @brief Coordinated thread pool
-  class thread_pool
-  {
-  public:
-    ~thread_pool();
-    //! @brief Join and delete all threads of the pool
-    void join();
-
-    //! @brief Detach all threads of the pool
-    void detach();
-
-    //! @brief Delete all threads of the pool
-    void clear();
-
-    //! @brief Instanciate new thread
-    template <class Fn, class... Args>
-    void thread(Fn&& fn, Args&&... args)
-    {
-      m_threads.push_back(new std::thread(fn, args...));
-    }
-
-  private:
-    std::vector<std::thread*> m_threads;
-  };
-}
-
-
-#endif //THREAD_HPP
diff --git a/src/complex.cpp b/src/complex.cpp
new file mode 100644
index 0000000..c55ca57
--- /dev/null
+++ b/src/complex.cpp
@@ -0,0 +1,42 @@
+#include "complex.hpp"
+
+const ztd::complex ztd::i(0,1);
+
+ztd::complex::complex(const double& a, const double& b)
+{
+  real=a;
+  im=b;
+}
+ztd::complex::complex(const ztd::complex& z)
+{
+  real=z.real;
+  im=z.im;
+}
+
+ztd::complex& ztd::complex::operator+=(const ztd::complex& z)
+{
+  real += z.real;
+  im += z.im;
+  return *this;
+}
+ztd::complex& ztd::complex::operator-=(const ztd::complex& z)
+{
+  real -= z.real;
+  im -= z.im;
+  return *this;
+}
+ztd::complex& ztd::complex::operator*=(const ztd::complex& z)
+{
+  double r=real;
+  real = real*z.real - im*z.im;
+  im = r*z.im + im*z.real;
+  return *this;
+}
+ztd::complex& ztd::complex::operator/=(const ztd::complex& z)
+{
+  double r=real;
+  double div = z.real*z.real + z.im*z.im;
+  real = (real*z.real + im*z.im)/div;
+  im   = (im*z.real - r*z.im)/div;
+  return *this;
+}
diff --git a/src/options.cpp b/src/options.cpp
index e98afd4..5b7dd62 100644
--- a/src/options.cpp
+++ b/src/options.cpp
@@ -142,8 +142,8 @@ ztd::option* ztd::option_set::find(char c)
 {
   for( auto it=m_options.begin() ; it!=m_options.end() ; it++ )
   {
-    if((*it).shortDef && (*it).charName == c)
-      return &(*it);
+    if(it->shortDef && it->charName == c)
+      return &*it;
   }
   return nullptr;
 }
@@ -152,8 +152,8 @@ ztd::option* ztd::option_set::find(std::string const& str)
 {
   for( auto it=m_options.begin() ; it!=m_options.end() ; it++ )
   {
-    if((*it).longDef && (*it).strName == str)
-    return &(*it);
+    if(it->longDef && it->strName == str)
+      return &*it;
   }
   return nullptr;
 }
diff --git a/src/thread.cpp b/src/thread.cpp
deleted file mode 100644
index af3c0c2..0000000
--- a/src/thread.cpp
+++ /dev/null
@@ -1,36 +0,0 @@
-#include "thread.hpp"
-
-ztd::thread_pool::~thread_pool()
-{
-  for(auto it : m_threads)
-  {
-    delete it;
-  }
-}
-
-void ztd::thread_pool::join()
-{
-  for(auto it : m_threads)
-  {
-    it->join();
-    delete it;
-  }
-  m_threads.clear();
-}
-
-void ztd::thread_pool::detach()
-{
-  for(auto it : m_threads)
-  {
-    it->detach();
-  }
-}
-
-void ztd::thread_pool::clear()
-{
-  for(auto it : m_threads)
-  {
-    delete it;
-  }
-  m_threads.clear();
-}