diff --git a/apps/regression/graph_options_controller.cpp b/apps/regression/graph_options_controller.cpp
index c1ddf0940..71bf107c1 100644
--- a/apps/regression/graph_options_controller.cpp
+++ b/apps/regression/graph_options_controller.cpp
@@ -2,6 +2,7 @@
 #include "app.h"
 #include "graph_controller.h"
 #include "regression_controller.h"
+#include <apps/apps_container.h>
 #include <assert.h>
 
 using namespace Shared;
@@ -56,7 +57,11 @@ bool GraphOptionsController::handleEvent(Ion::Events::Event event) {
 }
 
 int GraphOptionsController::numberOfRows() {
-  return k_numberOfParameterCells + 1;
+  int series = m_graphController->selectedSeriesIndex();
+  Poincare::Context * globContext = const_cast<AppsContainer *>(static_cast<const AppsContainer *>(app()->container()))->globalContext();
+  double * coefs = m_store->coefficientsForSeries(series, globContext);
+  int numberOfParameterCells = m_store->modelForSeries(series)->levelSetAvailable(coefs) ? k_numberOfParameterCells : k_numberOfParameterCells - 1;
+  return numberOfParameterCells + 1;
 }
 
 KDCoordinate GraphOptionsController::rowHeight(int j) {
@@ -80,7 +85,8 @@ KDCoordinate GraphOptionsController::cumulatedHeightFromIndex(int j) {
 int GraphOptionsController::indexFromCumulatedHeight(KDCoordinate offsetY) {
   int result = 0;
   int j = 0;
-  while (result < offsetY && j < numberOfRows()) {
+  int numberRows = numberOfRows();
+  while (result < offsetY && j < numberRows) {
     result += rowHeight(j++);
   }
   return (result < offsetY || offsetY == 0) ? j : j - 1;
@@ -113,14 +119,14 @@ int GraphOptionsController::typeAtLocation(int i, int j) {
 }
 
 void GraphOptionsController::willDisplayCellForIndex(HighlightCell * cell, int index) {
-  if (index < k_numberOfParameterCells) {
-    MessageTableCellWithChevron * myCell = (MessageTableCellWithChevron *)cell;
-    I18n::Message  titles[k_numberOfParameterCells] = {I18n::Message::XPrediction, I18n::Message::YPrediction};
-    myCell->setMessage(titles[index]);
-  } else {
-    assert(index == numberOfRows() - 1);
+  if (index == numberOfRows() - 1) {
     m_changeRegressionCell.setExpressionLayout(static_cast<Store *>(m_store)->modelForSeries(m_graphController->selectedSeriesIndex())->layout());
+    return;
   }
+  assert(index >=0 && index < k_numberOfParameterCells);
+  MessageTableCellWithChevron * myCell = (MessageTableCellWithChevron *)cell;
+  I18n::Message titles[k_numberOfParameterCells] = {I18n::Message::XPrediction, I18n::Message::YPrediction};
+  myCell->setMessage(titles[index]);
 }
 
 }
diff --git a/apps/regression/model/cubic_model.h b/apps/regression/model/cubic_model.h
index 0a41dae2f..b1dad2eb6 100644
--- a/apps/regression/model/cubic_model.h
+++ b/apps/regression/model/cubic_model.h
@@ -12,6 +12,7 @@ public:
   Poincare::ExpressionLayout * layout() override;
   I18n::Message formulaMessage() const override { return I18n::Message::CubicRegressionFormula; }
   double evaluate(double * modelCoefficients, double x) const override;
+  bool levelSetAvailable(double * modelCoefficients) const override { return false; }
   double levelSet(double * modelCoefficients, double y) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
   int numberOfCoefficients() const override { return 4; }
diff --git a/apps/regression/model/exponential_model.cpp b/apps/regression/model/exponential_model.cpp
index 338d2505b..f5e78ff6c 100644
--- a/apps/regression/model/exponential_model.cpp
+++ b/apps/regression/model/exponential_model.cpp
@@ -32,10 +32,19 @@ double ExponentialModel::evaluate(double * modelCoefficients, double x) const {
   return a*exp(b*x);
 }
 
+bool ExponentialModel::levelSetAvailable(double * modelCoefficients) const {
+  double a = modelCoefficients[0];
+  double b = modelCoefficients[1];
+  if (a == 0 || b == 0) {
+    return false;
+  }
+  return true;
+}
+
 double ExponentialModel::levelSet(double * modelCoefficients, double y) const {
   double a = modelCoefficients[0];
   double b = modelCoefficients[1];
-  if (a == 0 || b == 0 || y/a <= 0) {
+  if (!levelSetAvailable(modelCoefficients) || y/a <= 0) {
     return NAN;
   }
   return log(y/a)/b;
diff --git a/apps/regression/model/exponential_model.h b/apps/regression/model/exponential_model.h
index d51e00bb9..3e97f841b 100644
--- a/apps/regression/model/exponential_model.h
+++ b/apps/regression/model/exponential_model.h
@@ -12,6 +12,7 @@ public:
   Poincare::ExpressionLayout * layout() override;
   I18n::Message formulaMessage() const override { return I18n::Message::ExponentialRegressionFormula; }
   double evaluate(double * modelCoefficients, double x) const override;
+  bool levelSetAvailable(double * modelCoefficients) const override;
   double levelSet(double * modelCoefficients, double y) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
   int numberOfCoefficients() const override { return 2; }
diff --git a/apps/regression/model/linear_model.h b/apps/regression/model/linear_model.h
index 0249a841d..6554e4be8 100644
--- a/apps/regression/model/linear_model.h
+++ b/apps/regression/model/linear_model.h
@@ -12,6 +12,7 @@ public:
   Poincare::ExpressionLayout * layout() override;
   I18n::Message formulaMessage() const override { return I18n::Message::LinearRegressionFormula; }
   double evaluate(double * modelCoefficients, double x) const override;
+  bool levelSetAvailable(double * modelCoefficients) const override { return true; }
   double levelSet(double * modelCoefficients, double y) const override;
   virtual void fit(Store * store, int series, double * modelCoefficients, Poincare::Context * context) override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
diff --git a/apps/regression/model/logarithmic_model.cpp b/apps/regression/model/logarithmic_model.cpp
index dcc089a81..7329f2bfb 100644
--- a/apps/regression/model/logarithmic_model.cpp
+++ b/apps/regression/model/logarithmic_model.cpp
@@ -18,12 +18,17 @@ double LogarithmicModel::evaluate(double * modelCoefficients, double x) const {
   return a*log(x)+b;
 }
 
-double LogarithmicModel::levelSet(double * modelCoefficients, double y) const {
+bool LogarithmicModel::levelSetAvailable(double * modelCoefficients) const {
   double a = modelCoefficients[0];
-  double b = modelCoefficients[1];
-  if (a == 0) {
+  return a != 0;
+}
+
+double LogarithmicModel::levelSet(double * modelCoefficients, double y) const {
+  if (!levelSetAvailable(modelCoefficients)) {
     return NAN;
   }
+  double a = modelCoefficients[0];
+  double b = modelCoefficients[1];
   return exp((y-b)/a);
 }
 
diff --git a/apps/regression/model/logarithmic_model.h b/apps/regression/model/logarithmic_model.h
index 7e8dc6954..6a51436d7 100644
--- a/apps/regression/model/logarithmic_model.h
+++ b/apps/regression/model/logarithmic_model.h
@@ -12,6 +12,7 @@ public:
   Poincare::ExpressionLayout * layout() override;
   I18n::Message formulaMessage() const override { return I18n::Message::LogarithmicRegressionFormula; }
   double evaluate(double * modelCoefficients, double x) const override;
+  bool levelSetAvailable(double * modelCoefficients) const override;
   double levelSet(double * modelCoefficients, double y) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
   int numberOfCoefficients() const override { return 2; }
diff --git a/apps/regression/model/logistic_model.cpp b/apps/regression/model/logistic_model.cpp
index 45451621d..992850295 100644
--- a/apps/regression/model/logistic_model.cpp
+++ b/apps/regression/model/logistic_model.cpp
@@ -39,11 +39,21 @@ double LogisticModel::evaluate(double * modelCoefficients, double x) const {
   return c/(1.0+a*exp(-b*x));
 }
 
+bool LogisticModel::levelSetAvailable(double * modelCoefficients) const {
+  double a = modelCoefficients[0];
+  double b = modelCoefficients[1];
+  double c = modelCoefficients[2];
+  if (a == 0 || b == 0 || c == 0) {
+    return false;
+  }
+  return true;
+}
+
 double LogisticModel::levelSet(double * modelCoefficients, double y) const {
   double a = modelCoefficients[0];
   double b = modelCoefficients[1];
   double c = modelCoefficients[2];
-  if (a == 0 || b == 0 || c == 0 || y == 0) {
+  if (!levelSetAvailable(modelCoefficients) || y == 0) {
     return NAN;
   }
   double lnArgument = (c/y - 1)/a;
diff --git a/apps/regression/model/logistic_model.h b/apps/regression/model/logistic_model.h
index 6450ba116..7f5c28bb9 100644
--- a/apps/regression/model/logistic_model.h
+++ b/apps/regression/model/logistic_model.h
@@ -12,6 +12,7 @@ public:
   Poincare::ExpressionLayout * layout() override;
   I18n::Message formulaMessage() const override { return I18n::Message::LogisticRegressionFormula; }
   double evaluate(double * modelCoefficients, double x) const override;
+  bool levelSetAvailable(double * modelCoefficients) const override;
   double levelSet(double * modelCoefficients, double y) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
   int numberOfCoefficients() const override { return 3; }
diff --git a/apps/regression/model/model.h b/apps/regression/model/model.h
index ee5065a19..1b48453f0 100644
--- a/apps/regression/model/model.h
+++ b/apps/regression/model/model.h
@@ -29,6 +29,7 @@ public:
   virtual Poincare::ExpressionLayout * layout() = 0;
   virtual I18n::Message formulaMessage() const = 0;
   virtual double evaluate(double * modelCoefficients, double x) const = 0;
+  virtual bool levelSetAvailable(double * modelCoefficients) const = 0;
   virtual double levelSet(double * modelCoefficients, double y) const = 0;
   virtual void fit(Store * store, int series, double * modelCoefficients, Poincare::Context * context);
   virtual int numberOfCoefficients() const = 0;
diff --git a/apps/regression/model/power_model.cpp b/apps/regression/model/power_model.cpp
index 8130dcbd6..cbe67c0ac 100644
--- a/apps/regression/model/power_model.cpp
+++ b/apps/regression/model/power_model.cpp
@@ -29,10 +29,19 @@ double PowerModel::evaluate(double * modelCoefficients, double x) const {
   return a*pow(x,b);
 }
 
+bool PowerModel::levelSetAvailable(double * modelCoefficients) const {
+  double a = modelCoefficients[0];
+  double b = modelCoefficients[1];
+  if (a == 0 || b == 0) {
+    return false;
+  }
+  return true;
+}
+
 double PowerModel::levelSet(double * modelCoefficients, double y) const {
   double a = modelCoefficients[0];
   double b = modelCoefficients[1];
-  if (a == 0 || b == 0 || y/a <= 0) {
+  if (!levelSetAvailable(modelCoefficients) || y/a <= 0) {
     return NAN;
   }
   return exp(log(y/a)/b);
diff --git a/apps/regression/model/power_model.h b/apps/regression/model/power_model.h
index 86a3390e0..5216bd652 100644
--- a/apps/regression/model/power_model.h
+++ b/apps/regression/model/power_model.h
@@ -12,6 +12,7 @@ public:
   Poincare::ExpressionLayout * layout() override;
   I18n::Message formulaMessage() const override { return I18n::Message::PowerRegressionFormula; }
   double evaluate(double * modelCoefficients, double x) const override;
+  bool levelSetAvailable(double * modelCoefficients) const override;
   double levelSet(double * modelCoefficients, double y) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
   int numberOfCoefficients() const override { return 2; }
diff --git a/apps/regression/model/quadratic_model.h b/apps/regression/model/quadratic_model.h
index 3d35b3ad3..e9189f9eb 100644
--- a/apps/regression/model/quadratic_model.h
+++ b/apps/regression/model/quadratic_model.h
@@ -12,6 +12,7 @@ public:
   Poincare::ExpressionLayout * layout() override;
   I18n::Message formulaMessage() const override { return I18n::Message::QuadraticRegressionFormula; }
   double evaluate(double * modelCoefficients, double x) const override;
+  bool levelSetAvailable(double * modelCoefficients) const override { return false; }
   double levelSet(double * modelCoefficients, double y) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
   int numberOfCoefficients() const override { return 3; }
diff --git a/apps/regression/model/quartic_model.h b/apps/regression/model/quartic_model.h
index 087d3369a..3eb48ad07 100644
--- a/apps/regression/model/quartic_model.h
+++ b/apps/regression/model/quartic_model.h
@@ -12,6 +12,7 @@ public:
   Poincare::ExpressionLayout * layout() override;
   I18n::Message formulaMessage() const override { return I18n::Message::QuarticRegressionFormula; }
   double evaluate(double * modelCoefficients, double x) const override;
+  bool levelSetAvailable(double * modelCoefficients) const override { return false; }
   double levelSet(double * modelCoefficients, double y) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
   int numberOfCoefficients() const override { return 5; }
diff --git a/apps/regression/model/trigonometric_model.h b/apps/regression/model/trigonometric_model.h
index a2f14e62a..abf6e0985 100644
--- a/apps/regression/model/trigonometric_model.h
+++ b/apps/regression/model/trigonometric_model.h
@@ -12,6 +12,7 @@ public:
   Poincare::ExpressionLayout * layout() override;
   I18n::Message formulaMessage() const override { return I18n::Message::TrigonometricRegressionFormula; }
   double evaluate(double * modelCoefficients, double x) const override;
+  bool levelSetAvailable(double * modelCoefficients) const override { return false; }
   double levelSet(double * modelCoefficients, double y) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
   int numberOfCoefficients() const override { return 3; }