diff --git a/apps/probability/app.cpp b/apps/probability/app.cpp
index cc0ea62bc..d90d94788 100644
--- a/apps/probability/app.cpp
+++ b/apps/probability/app.cpp
@@ -20,13 +20,16 @@ const Image * App::Descriptor::icon() {
 }
 
 App::Snapshot::Snapshot() :
-  m_law{}
+  m_law{},
+  m_calculation{}
 {
   new(m_law) BinomialLaw();
+  new(m_calculation) LeftIntegralCalculation();
 }
 
 App::Snapshot::~Snapshot() {
   law()->~Law();
+  calculation()->~Calculation();
 }
 
 App * App::Snapshot::unpack(Container * container) {
@@ -42,9 +45,13 @@ Law * App::Snapshot::law() {
   return (Law *)m_law;
 }
 
+Calculation * App::Snapshot::calculation() {
+  return (Calculation *)m_calculation;
+}
+
 App::App(Container * container, Snapshot * snapshot) :
   TextFieldDelegateApp(container, snapshot, &m_stackViewController),
-  m_lawController(nullptr, snapshot->law()),
+  m_lawController(nullptr, snapshot->law(), snapshot->calculation()),
   m_stackViewController(&m_modalViewController, &m_lawController)
 {
 }
diff --git a/apps/probability/app.h b/apps/probability/app.h
index 45e72d55e..63a18f278 100644
--- a/apps/probability/app.h
+++ b/apps/probability/app.h
@@ -10,6 +10,9 @@
 #include "law/normal_law.h"
 #include "law/poisson_law.h"
 #include "law/uniform_law.h"
+#include "calculation/left_integral_calculation.h"
+#include "calculation/right_integral_calculation.h"
+#include "calculation/finite_integral_calculation.h"
 
 constexpr static size_t max(const int * data, int seed = 0) {
   return (*data == 0 ? seed : max(data+1, *data > seed ? *data : seed));
@@ -32,10 +35,14 @@ public:
     App * unpack(Container * container) override;
     Descriptor * descriptor() override;
     Law * law();
+    Calculation * calculation();
   private:
     constexpr static int k_lawSizes[] = {sizeof(BinomialLaw),sizeof(ExponentialLaw), sizeof(NormalLaw), sizeof(PoissonLaw), sizeof(UniformLaw), 0};
     constexpr static size_t k_lawSize = max(k_lawSizes);
     char m_law[k_lawSize];
+    constexpr static int k_calculationSizes[] = {sizeof(LeftIntegralCalculation),sizeof(FiniteIntegralCalculation), sizeof(RightIntegralCalculation), 0};
+    constexpr static size_t k_calculationSize = max(k_calculationSizes);
+    char m_calculation[k_calculationSize];
   };
 private:
   App(Container * container, Snapshot * snapshot);
diff --git a/apps/probability/calculation/calculation.h b/apps/probability/calculation/calculation.h
index 948acbe2f..32c0b24fa 100644
--- a/apps/probability/calculation/calculation.h
+++ b/apps/probability/calculation/calculation.h
@@ -9,8 +9,8 @@ class Calculation {
 public:
   enum class Type : uint8_t{
     LeftIntegral,
-    RightIntegral,
-    FiniteIntegral
+    FiniteIntegral,
+    RightIntegral
   };
   Calculation();
   virtual ~Calculation() = default;
diff --git a/apps/probability/calculation_controller.cpp b/apps/probability/calculation_controller.cpp
index f574bbd13..3ee6d4f4b 100644
--- a/apps/probability/calculation_controller.cpp
+++ b/apps/probability/calculation_controller.cpp
@@ -14,7 +14,7 @@ namespace Probability {
 
 CalculationController::ContentView::ContentView(Responder * parentResponder, CalculationController * calculationController, Calculation * calculation, Law * law) :
   m_titleView(MessageTextView(KDText::FontSize::Small, I18n::Message::ComputeProbability, 0.5f, 0.5f, Palette::GreyDark, Palette::WallScreen)),
-  m_lawCurveView(LawCurveView(law)),
+  m_lawCurveView(LawCurveView(law, calculation)),
   m_imageTableView(ImageTableView(parentResponder, calculation, calculationController)),
   m_calculationCell{EditableTextCell(parentResponder, calculationController, m_draftTextBuffer),
     EditableTextCell(parentResponder, calculationController, m_draftTextBuffer),
@@ -23,12 +23,6 @@ CalculationController::ContentView::ContentView(Responder * parentResponder, Cal
 {
 }
 
-void CalculationController::ContentView::setCalculation(Calculation * calculation, int index) {
-  m_calculation = calculation;
-  m_lawCurveView.setCalculation(calculation);
-  m_imageTableView.setCalculation(calculation, index);
-}
-
 int CalculationController::ContentView::numberOfSubviews() const {
   return 2*m_calculation->numberOfParameters() + 3;
 }
@@ -130,21 +124,15 @@ EditableTextCell * CalculationController::ContentView::calculationCellAtIndex(in
   return &m_calculationCell[index];
 }
 
-CalculationController::CalculationController(Responder * parentResponder, Law * law) :
+CalculationController::CalculationController(Responder * parentResponder, Law * law, Calculation * calculation) :
   ViewController(parentResponder),
-  m_calculation(new LeftIntegralCalculation()),
+  m_calculation(calculation),
   m_contentView(ContentView(this, this, m_calculation, law)),
   m_law(law),
   m_highlightedSubviewIndex(1)
 {
   assert(law != nullptr);
-}
-
-CalculationController::~CalculationController() {
-  if (m_calculation) {
-    delete m_calculation;
-    m_calculation = nullptr;
-  }
+  assert(calculation != nullptr);
 }
 
 View * CalculationController::view() {
@@ -160,26 +148,25 @@ void CalculationController::reload() {
   m_contentView.lawCurveView()->reload();
 }
 
-void CalculationController::setCalculationAccordingToIndex(int index) {
-  if (m_calculation != nullptr) {
-    delete m_calculation;
-    m_calculation = nullptr;
+void CalculationController::setCalculationAccordingToIndex(int index, bool forceReinitialisation) {
+  if ((int)m_calculation->type() == index && !forceReinitialisation) {
+    return;
   }
+  m_calculation->~Calculation();
   switch (index) {
     case 0:
-      m_calculation = new LeftIntegralCalculation();
+      new(m_calculation) LeftIntegralCalculation();
       break;
     case 1:
-      m_calculation = new FiniteIntegralCalculation();
+      new(m_calculation) FiniteIntegralCalculation();
       break;
     case 2:
-      m_calculation = new RightIntegralCalculation();
+      new(m_calculation) RightIntegralCalculation();
       break;
     default:
      return;
   }
   m_calculation->setLaw(m_law);
-  m_contentView.setCalculation(m_calculation, index);
 }
 
 bool CalculationController::handleEvent(Ion::Events::Event event) {
diff --git a/apps/probability/calculation_controller.h b/apps/probability/calculation_controller.h
index 17b2bdb97..b64c3ae9c 100644
--- a/apps/probability/calculation_controller.h
+++ b/apps/probability/calculation_controller.h
@@ -12,16 +12,11 @@ namespace Probability {
 
 class CalculationController : public ViewController, public Shared::TextFieldDelegate {
 public:
-  CalculationController(Responder * parentResponder, Law * law);
-  ~CalculationController();
-  CalculationController(const CalculationController& other) = delete;
-  CalculationController(CalculationController&& other) = delete;
-  CalculationController& operator=(const CalculationController& other) = delete;
-  CalculationController& operator=(CalculationController&& other) = delete;
+  CalculationController(Responder * parentResponder, Law * law, Calculation * calculation);
   View * view() override;
   const char * title() override;
   void reload();
-  void setCalculationAccordingToIndex(int index);
+  void setCalculationAccordingToIndex(int index, bool forceReinitialisation = false);
   bool handleEvent(Ion::Events::Event event) override;
   void didBecomeFirstResponder() override;
   void selectSubview(int subviewIndex);
diff --git a/apps/probability/image_table_view.cpp b/apps/probability/image_table_view.cpp
index 6cccd1e7c..3830597b8 100644
--- a/apps/probability/image_table_view.cpp
+++ b/apps/probability/image_table_view.cpp
@@ -58,15 +58,10 @@ ImageTableView::ImageTableView(Responder * parentResponder, Calculation * calcul
   Responder(parentResponder),
   m_selectableTableView(this, this, 0, 0, 0, 0, 0, 0, this, nullptr, false, false),
   m_isSelected(false),
-  m_selectedIcon(0),
   m_calculation(calculation),
   m_calculationController(calculationController)
 {
-}
-
-void ImageTableView::setCalculation(Calculation * calculation, int index) {
-  m_calculation = calculation;
-  m_selectedIcon = index;
+  assert(m_calculation != nullptr);
 }
 
 void ImageTableView::didBecomeFirstResponder() {
@@ -104,7 +99,7 @@ void ImageTableView::select(bool select) {
     willDisplayCellForIndex(m_selectableTableView.cellAtLocation(0,0), 0);
   } else {
     m_isSelected = select;
-    m_selectableTableView.selectCellAtLocation(0, m_selectedIcon);
+    m_selectableTableView.selectCellAtLocation(0, (int)m_calculation->type());
   }
 }
 
@@ -138,7 +133,7 @@ void ImageTableView::willDisplayCellForIndex(HighlightCell * cell, int index) {
   const Image *  images[3] = {ImageStore::Calcul1Icon, ImageStore::Calcul2Icon, ImageStore::Calcul3Icon};
   const Image * focusedImages[3] = {ImageStore::FocusedCalcul1Icon, ImageStore::FocusedCalcul2Icon, ImageStore::FocusedCalcul3Icon};
   if (!m_isSelected) {
-    myCell->setImage(images[m_selectedIcon], focusedImages[m_selectedIcon]);
+    myCell->setImage(images[(int)m_calculation->type()], focusedImages[(int)m_calculation->type()]);
   } else {
     myCell->setImage(images[index], focusedImages[index]);
   }
diff --git a/apps/probability/law_controller.cpp b/apps/probability/law_controller.cpp
index d65ca845a..2c9cd7edc 100644
--- a/apps/probability/law_controller.cpp
+++ b/apps/probability/law_controller.cpp
@@ -51,13 +51,13 @@ static I18n::Message sMessages[] = {
   I18n::Message::Poisson
 };
 
-LawController::LawController(Responder * parentResponder, Law * law) :
+LawController::LawController(Responder * parentResponder, Law * law, Calculation * calculation) :
   ViewController(parentResponder),
   m_selectableTableView(this, this, 0, 1, Metric::CommonTopMargin-ContentView::k_titleMargin, Metric::CommonRightMargin,
     Metric::CommonBottomMargin, Metric::CommonLeftMargin, this),
   m_contentView(&m_selectableTableView),
   m_law(law),
-  m_parametersController(nullptr, law)
+  m_parametersController(nullptr, law, calculation)
 {
   m_messages = sMessages;
   assert(m_law != nullptr);
@@ -139,6 +139,7 @@ void Probability::LawController::setLawAccordingToIndex(int index) {
     default:
      return;
   }
+  m_parametersController.reinitCalculation();
 }
 
 }
diff --git a/apps/probability/law_controller.h b/apps/probability/law_controller.h
index bd8261d74..8ffa95f67 100644
--- a/apps/probability/law_controller.h
+++ b/apps/probability/law_controller.h
@@ -11,7 +11,7 @@ namespace Probability {
 
 class LawController : public ViewController, public SimpleListViewDataSource, public SelectableTableViewDataSource {
 public:
-  LawController(Responder * parentResponder, Law * m_law);
+  LawController(Responder * parentResponder, Law * m_law, Calculation * calculation);
   View * view() override;
   bool handleEvent(Ion::Events::Event event) override;
   void didBecomeFirstResponder() override;
diff --git a/apps/probability/law_curve_view.cpp b/apps/probability/law_curve_view.cpp
index 074fcb3b3..76bd3e8dd 100644
--- a/apps/probability/law_curve_view.cpp
+++ b/apps/probability/law_curve_view.cpp
@@ -6,17 +6,14 @@ using namespace Shared;
 
 namespace Probability {
 
-LawCurveView::LawCurveView(Law * law) :
+LawCurveView::LawCurveView(Law * law, Calculation * calculation) :
   CurveView(law, nullptr, nullptr, nullptr),
   m_labels{},
   m_law(law),
-  m_calculation(nullptr)
+  m_calculation(calculation)
 {
   assert(law != nullptr);
-}
-
-void LawCurveView::setCalculation(Calculation * calculation) {
-  m_calculation = calculation;
+  assert(calculation != nullptr);
 }
 
 void LawCurveView::drawRect(KDContext * ctx, KDRect rect) const {
diff --git a/apps/probability/law_curve_view.h b/apps/probability/law_curve_view.h
index 64321d55d..46d92afdf 100644
--- a/apps/probability/law_curve_view.h
+++ b/apps/probability/law_curve_view.h
@@ -12,8 +12,7 @@ namespace Probability {
 
 class LawCurveView : public Shared::CurveView {
 public:
-  LawCurveView(Law * law);
-  void setCalculation(Calculation * calculation);
+  LawCurveView(Law * law, Calculation * calculation);
   void drawRect(KDContext * ctx, KDRect rect) const override;
 protected:
   char * label(Axis axis, int index) const override;
diff --git a/apps/probability/parameters_controller.cpp b/apps/probability/parameters_controller.cpp
index c4b4509d0..fe0ba2c8e 100644
--- a/apps/probability/parameters_controller.cpp
+++ b/apps/probability/parameters_controller.cpp
@@ -67,12 +67,12 @@ void ParametersController::ContentView::layoutSubviews() {
 
 /* Parameters Controller */
 
-ParametersController::ParametersController(Responder * parentResponder, Law * law) :
+ParametersController::ParametersController(Responder * parentResponder, Law * law, Calculation * calculation) :
   FloatParameterController(parentResponder),
   m_selectableTableView(nullptr),
   m_menuListCell{},
   m_law(law),
-  m_calculationController(nullptr, law)
+  m_calculationController(nullptr, law, calculation)
 {
   assert(m_law != nullptr);
 }
@@ -81,6 +81,10 @@ const char * ParametersController::title() {
   return I18n::translate(m_law->title());
 }
 
+void ParametersController::reinitCalculation() {
+  m_calculationController.setCalculationAccordingToIndex(0, true);
+}
+
 void ParametersController::viewWillAppear() {
   FloatParameterController::viewWillAppear();
   for (int i = 0; i < m_law->numberOfParameter(); i++) {
@@ -125,6 +129,7 @@ bool ParametersController::setParameterAtIndex(int parameterIndex, float f) {
     return false;
   }
   m_law->setParameterAtIndex(f, parameterIndex);
+  m_calculationController.setCalculationAccordingToIndex(0, true);
   return true;
 }
 
@@ -137,7 +142,6 @@ bool ParametersController::textFieldDidFinishEditing(TextField * textField, cons
 }
 
 void ParametersController::buttonAction() {
-  m_calculationController.setCalculationAccordingToIndex(0);
   m_calculationController.selectSubview(1);
   m_calculationController.reload();
   StackViewController * stack = stackController();
diff --git a/apps/probability/parameters_controller.h b/apps/probability/parameters_controller.h
index 5df60faf0..d2cb55171 100644
--- a/apps/probability/parameters_controller.h
+++ b/apps/probability/parameters_controller.h
@@ -10,8 +10,9 @@ namespace Probability {
 
 class ParametersController : public Shared::FloatParameterController {
 public:
-  ParametersController(Responder * parentResponder, Law * m_law);
+  ParametersController(Responder * parentResponder, Law * m_law, Calculation * calculation);
   const char * title() override;
+  void reinitCalculation();
   void viewWillAppear() override;
   int numberOfRows() override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;