Updated the CanFunctionAnalysisBePerformed api to use the updated one with variableIsNotX error handling. Updated the UI to reflect the new descriptive error case to show an informative error.

src/CalcViewModel/GraphingCalculator/EquationViewModel.cpp

@@ -63,6 +63,10 @@ namespace CalculatorApp::ViewModel
             {
                 AnalysisErrorString = m_resourceLoader->GetString(L"KGFAnalysisNotSupported");
             }
+            else if (graphEquation->AnalysisError == static_cast<int>(AnalysisErrorType::VariableIsNotX))
+            {
+                AnalysisErrorString = m_resourceLoader->GetString(L"KGFVariableIsNotX");
+            }
             return;
         }
 

src/CalcViewModel/GraphingCalculatorEnums.h

@@ -23,6 +23,7 @@ namespace CalculatorApp
     {
         NoError,
         AnalysisCouldNotBePerformed,
-        AnalysisNotSupported
+        AnalysisNotSupported,
+        VariableIsNotX
     };
 }

src/Calculator/Resources/en-US/Resources.resw

@@ -4070,6 +4070,10 @@
   <data name="KGFAnalysisNotSupported" xml:space="preserve">
     <value>Analysis is not supported for this function.</value>
     <comment>Error displayed when graph analysis is not supported or had an error.</comment>
+  </data>
+    <data name="KGFVariableIsNotX" xml:space="preserve">
+    <value>Analysis is only supported for functions in the f(x) format. Example: y=x</value>
+    <comment>Error displayed when graph analysis detects the function format is not f(x).</comment>
   </data>
   <data name="Maxima" xml:space="preserve">
     <value>Maxima</value>

src/GraphControl/Control/Grapher.cpp

@@ -254,17 +254,22 @@ namespace GraphControl
                 vector<Equation ^> equationVector;
                 equationVector.push_back(equation);
                 UpdateGraphOptions(graph->GetOptions(), equationVector);
-
+                bool variableIsNotX;
-                if (analyzer->CanFunctionAnalysisBePerformed())
+                if (analyzer->CanFunctionAnalysisBePerformed(variableIsNotX))
                 {
                     if (S_OK
                         == analyzer->PerformFunctionAnalysis(
-                            (Graphing::Analyzer::NativeAnalysisType)Graphing::Analyzer::PerformAnalysisType::PerformAnalysisType_All))
+                            (Graphing::Analyzer::NativeAnalysisType)Graphing::Analyzer::PerformAnalysisType::PerformAnalysisType_All)
+                        && !variableIsNotX)
                     {
                         Graphing::IGraphFunctionAnalysisData functionAnalysisData = m_solver->Analyze(analyzer.get());
                         return KeyGraphFeaturesInfo::Create(functionAnalysisData);
                     }
                 }
+                else if (variableIsNotX)
+                {
+                    return KeyGraphFeaturesInfo::Create(CalculatorApp::AnalysisErrorType::VariableIsNotX);
+                }
                 else
                 {
                     return KeyGraphFeaturesInfo::Create(CalculatorApp::AnalysisErrorType::AnalysisNotSupported);

src/GraphingInterfaces/IGraphAnalyzer.h

@@ -16,9 +16,9 @@ namespace Graphing::Analyzer
 	struct IGraphAnalyzer : public NonCopyable, public NonMoveable
 	{
 		virtual ~IGraphAnalyzer() = default;
-		virtual bool CanFunctionAnalysisBePerformed() = 0;
+        virtual bool CanFunctionAnalysisBePerformed(bool& variableIsNotX) = 0;
 		virtual HRESULT PerformFunctionAnalysis(NativeAnalysisType analysisType) = 0;
 		virtual HRESULT GetAnalysisTypeCaption(const AnalysisType type, std::wstring& captionOut) const = 0;
 		virtual HRESULT GetMessage(const GraphAnalyzerMessage msg, std::wstring& msgOut) const = 0;
 	};
-}
+}