public function testEvaluateWithFunction()
{
$Eval = new EvalMath();
$Eval->evaluate('f(x,y) = x^2 + y^2 - 2x*y + 1');
$result = $Eval->evaluate('3*f(1,3);');
$this->assertIdentical('15.000', $result);
$result = $Eval->funcs();
$this->assertIdentical(array('f(x,y)'), $result);
$result = $Eval->evaluate('sin(pi/2)');
$this->assertIdentical('1.000', $result);
$result = $Eval->evaluate('log10(1)');
$this->assertIdentical('0.000', $result);
$Eval->clear();
$Eval->evaluate('f(x) = sqrt(x)');
$result = $Eval->evaluate('f(4)');
$this->assertIdentical('2.000', $result);
$Eval->evaluate('g(x) = sqrt(2x) + ln(e)');
$result = $Eval->evaluate('g(2)');
$this->assertIdentical('3.000', $result);
unset($Eval);
}