is Constant

src/main/java/formula/Addition.java

@@ -25,4 +25,9 @@ public class Addition implements Formula{
     public Formula derivative() {
         return new Addition (leftMember.derivative(), rightMember.derivative());
     }
+    @Override
+    public Boolean isConstant() {
+        return leftMember.isConstant() && rightMember.isConstant();
+    }
+
 }

src/main/java/formula/Constant.java

@@ -58,4 +58,11 @@ public class Constant implements Formula {
     if(!(obj instanceof Constant constant)) return false;
     return this.value == constant.value;
   }
+
+  @Override
+  public Boolean isConstant() {
+    return true;
   }
+
+  }
+

src/main/java/formula/Cosine.java

@@ -8,6 +8,8 @@ public class Cosine implements Formula{
 
 
     public Cosine (Formula formule){
+        this.formule=formule;
+
 
 
     }
@@ -26,5 +28,10 @@ public class Cosine implements Formula{
     public Formula derivative() {
         return new Multiplication (formule.derivative(),new Opposite(new Sine(formule)));
     }
+
+    @Override
+    public Boolean isConstant() {
+        return formule.isConstant();
+    }
 }
 

src/main/java/formula/Division.java

@@ -26,4 +26,10 @@ public class Division implements Formula {
         return new Division(new Subtraction(new Multiplication(leftMember.derivative(),rightMember),new Multiplication(leftMember,rightMember.derivative())),new Multiplication(rightMember,rightMember
         ));
     }
+
+    @Override
+    public Boolean isConstant() {
+        return leftMember.isConstant() && rightMember.isConstant();
+
+    }
 }

src/main/java/formula/Exponential.java

@@ -6,6 +6,7 @@ public class Exponential implements Formula {
 
 
     public Exponential (Formula formule){
+        this.formule = formule;
 
 
     }
@@ -22,6 +23,11 @@ public class Exponential implements Formula {
 
     @Override
     public Formula derivative() {
-        return new Multiplication(new Exponential(this.formule),formule.derivative());
+        return new Multiplication(new Exponential(formule),formule.derivative());
+    }
+
+    @Override
+    public Boolean isConstant() {
+        return formule.isConstant();
     }
 }

src/main/java/formula/Formula.java

@@ -22,4 +22,8 @@ public interface Formula {
    */
   Formula derivative();
 
+  Boolean isConstant();
+
+
+
 }

src/main/java/formula/Logarithm.java

 package formula;
 
-public class Logarithm implements Formula
+public class Logarithm implements Formula{
 
     private Formula formule;
 
 
     public Logarithm  (Formula formule){
+        this.formule=formule;
 
 
     }
@@ -24,6 +25,10 @@ public class Logarithm implements Formula
     public Formula derivative() {
         return new Division(formule.derivative(),formule);
     }
+
+    @Override
+    public Boolean isConstant() {
+        return formule.isConstant();
     }
-{
 }
+

src/main/java/formula/Multiplication.java

@@ -25,5 +25,10 @@ public class Multiplication implements Formula {
     public Formula derivative() {
         return new Addition (new Multiplication(leftMember.derivative(),rightMember),new Multiplication(leftMember,rightMember.derivative()));
     }
+
+    @Override
+    public Boolean isConstant() {
+        return leftMember.isConstant() && rightMember.isConstant();
+    }
 }
 

src/main/java/formula/Opposite.java

@@ -6,6 +6,8 @@ public class Opposite implements Formula {
 
 
     public Opposite (Formula formule){
+        this.formule=formule;
+
 
 
     }
@@ -24,4 +26,9 @@ public class Opposite implements Formula {
     public Formula derivative() {
         return new Opposite(formule.derivative());
     }
+
+    @Override
+    public Boolean isConstant() {
+        return formule.isConstant();
+    }
 }
\ No newline at end of file

src/main/java/formula/Sine.java

@@ -5,6 +5,8 @@ public class Sine implements Formula{
 
 
     public Sine (Formula formule){
+        this.formule=formule;
+
 
 
     }
@@ -23,4 +25,9 @@ public class Sine implements Formula{
     public Formula derivative() {
         return new Multiplication(formule.derivative(),new Cosine(formule));
     }
+
+    @Override
+    public Boolean isConstant() {
+        return formule.isConstant();
+    }
 }

src/main/java/formula/Subtraction.java

@@ -25,4 +25,9 @@ public class Subtraction implements Formula {
     public Formula derivative() {
         return new Subtraction (leftMember.derivative(), rightMember.derivative());
     }
+
+    @Override
+    public Boolean isConstant() {
+        return leftMember.isConstant() && rightMember.isConstant();
+    }
 }

src/main/java/formula/VariableX.java

@@ -19,5 +19,10 @@ public class VariableX implements Formula {
     public Formula derivative() {
         return new Constant(1);
     }
+
+    @Override
+    public Boolean isConstant() {
+        return false;
+    }
 }
 

src/main/java/viewer/FunctionList.java

@@ -46,6 +46,10 @@ class FunctionList {
     // Exp
     PlottableFunction functioneXP = new PlottableFunction(new Exponential(new VariableX()), "IM");
     addFunctionAndItsDerivative(functioneXP);
+
+    //log
+    PlottableFunction functionLOG = new PlottableFunction(new Logarithm(new VariableX()), "ML");
+    addFunctionAndItsDerivative(functionLOG);
   }
   void toggleFunction(PlottableFunction function) {
     if (function.isPlotted()){