public function testCanEvaluateExponentiation()
{
$x = $this->variables['x'];
$this->assertResult('x^3', Complex::pow($x, 3));
$this->assertResult('x^x^x', Complex::pow($x, Complex::pow($x, $x)));
$this->assertResult('(-1)^(-1)', Complex::parse(-1));
}
/**
* Evaluate an ExpressionNode
*
* Computes the value of an ExpressionNode `x op y`
* where `op` is one of `+`, `-`, `*`, `/` or `^`
*
* @throws UnknownOperatorException if the operator is something other than
* `+`, `-`, `*`, `/` or `^`
*
* @param ExpressionNode $node AST to be evaluated
* @retval float
*/
public function visitExpressionNode(ExpressionNode $node)
{
$operator = $node->getOperator();
$a = $node->getLeft()->accept($this);
if ($node->getRight()) {
$b = $node->getRight()->accept($this);
} else {
$b = null;
}
// Perform the right operation based on the operator
switch ($operator) {
case '+':
return Complex::add($a, $b);
case '-':
if ($b === null) {
return Complex::mul($a, -1);
}
return Complex::sub($a, $b);
case '*':
return Complex::mul($a, $b);
case '/':
return Complex::div($a, $b);
case '^':
// This needs to be improved.
return Complex::pow($a, $b);
default:
throw new UnknownOperatorException($operator);
}
}
public function testCanComputePowers()
{
$z = new Complex(1, 2);
$this->assertEquals(new Complex(-3, 4), Complex::pow($z, 2));
$this->assertEquals(new Complex(-11, -2), Complex::pow($z, 3));
$this->assertEquals(new Complex(1 / 5, -2 / 5), Complex::pow($z, -1));
$this->assertEquals(new Complex(0.229140186, 0.2381701151), Complex::pow($z, new Complex(0, 1)));
}
