https://github.com/crowlogic/arb4j/issues/253

README.md

@@ -48,8 +48,8 @@ try (Real x = new Real("25", 128)) {
 
 #### Expression Compiler
 - The [arb.expressions](https://github.com/crowlogic/arb4j/tree/master/src/main/java/arb/expressions) package in arb4j includes tools for compiling mathematical [expressions](https://github.com/crowlogic/arb4j/blob/master/src/main/java/arb/expressions/Expression.java) directly into Java bytecode, saving milleniums of development time, reducing the need to laborously and tediously write new code for each different formula to be evaluated whilst also ensuring efficiency and correctness; it would be challenging to write code manually that would significantly outperform the generated code
-##### ExpressionAnalyzer
-The [ExpressionAnalyzer](https://github.com/crowlogic/arb4j/tree/master/src/main/java/arb/viz/ExpressionAnalyzer.java) provides a tree-list view that shows the abstract-syntex-tree that constitutes
+##### Expressor
+The [Expressor](https://github.com/crowlogic/arb4j/tree/master/src/main/java/arb/expressions/viz/Expressor.java) program provides a tree-list view that shows the abstract-syntex-tree that constitutes
 a given expression and the intermediate values that combine to produce a given result.
 
 ![Screenshot from 2024-08-25 21-42-44](https://github.com/user-attachments/assets/cd1d71de-bcef-4be6-b25a-3c41293de158)

expressions/P.yaml

@@ -0,0 +1,16 @@
+--- !!arb.expressions.SerializedExpression
+coDomain: arb.RationalFunction
+context:
+  input:
+  - arb.Integer
+  - 2
+  β:
+  - arb.Real
+  - '-0.5'
+  α:
+  - arb.Real
+  - '-0.5'
+domain: arb.Integer
+expression: n➔when(n=0,1,n=1,(C(1)*x-β+α)/2.0,else,(A(n)*P(n-1)-B(n)*P(n-2))/E(n))
+function: arb.functions.rational.RationalFunctionSequence
+...

src/main/java/arb/expressions/nodes/Node.java

@@ -269,7 +269,12 @@ public Node<D, R, F> mul(Node<D, R, F> multiplicand)
 
   public Node<D, R, F> pow(int i)
   {
-    return pow(LiteralConstantNode.of(expression, i));
+    return pow(nodeOf(i));
+  }
+
+  public Node<D, R, F> nodeOf(int i)
+  {
+    return LiteralConstantNode.of(expression, i);
   }
 
   public Node<D, R, F> neg()
@@ -280,12 +285,12 @@ public Node<D, R, F> neg()
 
   public Node<D, R, F> sub(int i)
   {
-    return sub(LiteralConstantNode.of(expression, i));
+    return sub(nodeOf(i));
   }
 
   public Node<D, R, F> div(int i)
   {
-    return div(LiteralConstantNode.of(expression, i));
+    return div(nodeOf(i));
   }
 
   public Node<D, R, F> pow(String exponent)
@@ -296,23 +301,34 @@ public Node<D, R, F> pow(String exponent)
 
   public Node<D, R, F> cos()
   {
-    return new FunctionNode<>("cos",
+    return apply("cos");
+  }
+
+  public Node<D, R, F> apply(String functionName)
+  {
+    return new FunctionNode<>(functionName,
                               this,
                               expression);
   }
 
   public Node<D, R, F> sin()
   {
-    return new FunctionNode<>("sin",
-                              this,
-                              expression);
+    return apply("sin");
   }
 
   public Node<D, R, F> sqrt()
   {
-    return new FunctionNode<>("sqrt",
-                              this,
-                              expression);
+    return apply("sqrt");
+  }
+
+  public Node<D, R, F> tan()
+  {
+    return apply("tan");
+  }
+
+  public Node<D, R, F> tanh()
+  {
+    return apply("tanh");
   }
 
 }

src/main/java/arb/expressions/nodes/unary/FunctionNode.java

@@ -465,7 +465,7 @@ private Node<D, R, F> differentiateBuiltinFunction()
     switch (functionName)
     {
     case "arcsin":
-      var one = expression.newLiteralConstant(1);
+      var one = nodeOf(1);
       return one.div(one.sub(arg.pow(2)).sqrt());
     case "sin":
       return arg.cos();
@@ -474,7 +474,9 @@ private Node<D, R, F> differentiateBuiltinFunction()
     case "exp":
       return this;
     case "log":
-      return expression.newLiteralConstant(1).div(arg);
+      return nodeOf(1).div(arg);
+    case "tanh":
+      return nodeOf(1).sub(arg.tanh().pow(2));
     default:
       throw new UnsupportedOperationException("Derivative not implemented for function: " + functionName);
     }