diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..e440c92
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,24 @@
+
+Copyright (c) 2014, 2015, Markus Rosenstihl, Condensed Matter Physics Institute, Technische Universität Darmstadt
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification, 
+are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this 
+list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice, 
+this list of conditions and the following disclaimer in the documentation and/or 
+other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND 
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR 
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON 
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/data/Container.py b/data/Container.py
index 6db4396..71eb450 100644
--- a/data/Container.py
+++ b/data/Container.py
@@ -3,7 +3,7 @@
 from PyQt4.QtGui import QColor
 import numpy as np
 
-from libmath import yafflib
+from libmath import yafflib, functions
 
 from libmath.BDSlib import id_to_color
 from container_base import BaseContainer
@@ -13,7 +13,7 @@ import gui.container_widgets
 
 __author__ = 'markusro'
 
-
+# FIXME: why are the functions implemented again? Better to use function_library!!
 class Conductivity(BaseContainer):
     def __init__( self, plt_imag=None, plt_real=None, limits=None ):
         super(Conductivity, self).__init__(plt_real=plt_real, plt_imag=plt_imag, limits=limits)
@@ -23,13 +23,16 @@ class Conductivity(BaseContainer):
         self.id_string = "cond"
 
         self.param_number = 3
+    def function(self, p ,x):
+        return functions.cond_cmplx(p,x)
+
+    # def function( self, p, x ):
+    #     om = 2*np.pi*x
+    #     sgma, isgma, n = p
+    #     cond = sgma/(om**n)+isgma/(1j*om**n)  # Jonscher (Universal Dielectric Response: e",e' prop sigma/omega**n
+    #     cplx = np.array([cond.real, -cond.imag])
+    #     return cplx
 
-    def function( self, p, x ):
-        om = 2*np.pi*x
-        sgma, isgma, n = p
-        cond = sgma/(om**n)+isgma/(1j*om**n)  # Jonscher (Universal Dielectric Response: e",e' prop sigma/omega**n
-        cplx = np.array([cond.real, -cond.imag])
-        return cplx
 
 
 class PowerComplex(BaseContainer):
diff --git a/data/container_base.py b/data/container_base.py
index a2d1e87..304a39b 100644
--- a/data/container_base.py
+++ b/data/container_base.py
@@ -11,6 +11,8 @@ class BaseContainer(QObject):
     """
     This class provides placeholders (or default) methods for "container" objects.
     These objects are basically the different fit elements for dielectric spectroscopy.
+    Specific containers are implemented in  the container.py module.
+
     """
     # TODO generalize the base class so that we can use plugins (self-contained fit functions)
     changedData = pyqtSignal()
diff --git a/data/data.py b/data/data.py
index eeac5d7..19fc3b7 100644
--- a/data/data.py
+++ b/data/data.py
@@ -7,7 +7,7 @@ class Daten(QObject):
     data_changed_signal = pyqtSignal(list, list, list)
 
     def __init__(self, x=None, y_real=None, y_imag=None):
-        super(Daten, self).__init__(None)
+        super(Daten, self).__init__()
         self._data = (x, y_real, y_imag)
 
     def get_data(self):
diff --git a/gui/graphs.py b/gui/graphs.py
index 17fccf5..b8382b0 100644
--- a/gui/graphs.py
+++ b/gui/graphs.py
@@ -2,7 +2,7 @@
 from PyQt4.QtCore import pyqtSignal
 from PyQt4.QtGui import QColor
 from data.data import Daten
-from libmath.function_library import ModelFunction
+from libmath.functions import ModelFunction
 
 __author__ = 'markusro'
 
diff --git a/libmath/function_library.py b/libmath/functions.py
similarity index 100%
rename from libmath/function_library.py
rename to libmath/functions.py
diff --git a/qds.py b/qds.py
index cd61625..146dff3 100755
--- a/qds.py
+++ b/qds.py
@@ -348,6 +348,7 @@ class AppWindow(QMainWindow):
 
 
     #TODO: need interface/method for adding function blocks, this is too repetitive
+    #TODO: start parameters have to be factored out for the above
     def addYaff( self, pos ):
         _yaff = YAFF(plt_real=self.ui.pgPlotWidget_real,
                      plt_imag=self.ui.pgPlotWidget_imag,