public static void main(String[] args) {
while (true) {
System.out.println("\n\nEnter an expression, or press return to end.");
System.out.print("\n? ");
TextIO.skipBlanks();
if (TextIO.peek() == '\n') break;
try {
ExpNode exp = expressionTree();
TextIO.skipBlanks();
if (TextIO.peek() != '\n') throw new ParseError("Extra data after end of expression.");
TextIO.getln();
ExpNode deriv = exp.derivative();
System.out.println("\nA fully parenthesized expression for the derivative is:");
System.out.print(" ");
deriv.printInfix();
System.out.println();
System.out.println("\nValue of derivative at x = 0 is " + deriv.value(0));
System.out.println("Value of derivative at x = 1 is " + deriv.value(1));
System.out.println("Value of derivative at x = 2 is " + deriv.value(2));
System.out.println("Value of derivative at x = 3 is " + deriv.value(3));
System.out.println("\nOrder of postfix evaluation for derivative is:\n");
deriv.printStackCommands();
} catch (ParseError e) {
System.out.println("\n*** Error in input: " + e.getMessage());
System.out.println("*** Discarding input: " + TextIO.getln());
}
}
System.out.println("\n\nDone.");
} // end main()
ExpNode derivative() {
// Apply the derivative formulas.
switch (op) {
case '+':
return new BinOpNode('+', left.derivative(), right.derivative());
case '-':
return new BinOpNode('-', left.derivative(), right.derivative());
case '*':
return new BinOpNode(
'+',
new BinOpNode('*', left, right.derivative()),
new BinOpNode('*', right, left.derivative()));
case '/':
return new BinOpNode(
'/',
new BinOpNode(
'-',
new BinOpNode('*', right, left.derivative()),
new BinOpNode('*', left, right.derivative())),
new BinOpNode('*', right, right));
default:
return null;
}
}
ExpNode derivative() {
// The derivative of -A is -(derivative of A).
return new UnaryMinusNode(operand.derivative());
}
