public function testAcos()
{
$this->assertTrue(CMathf::equalsZt(CMathf::acos(1.0), 0.0));
$this->assertTrue(CMathf::equalsZt(CMathf::acos(0.0), CMathf::HALF_PI));
$this->assertTrue(CMathf::equalsZt(CMathf::acos(0.707106781), CMathf::PI / 4));
$this->assertTrue(CMathf::equalsZt(CMathf::acos(0.8660254040000001), CMathf::PI / 6));
// Special cases.
$this->assertTrue(CMathf::equalsZt(CMathf::acos(1.5), 0.0));
$this->assertTrue(CMathf::equalsZt(CMathf::acos(2.0), 0.0));
$this->assertTrue(CMathf::equalsZt(CMathf::acos(-3.0), CMathf::PI));
$this->assertTrue(CMathf::equalsZt(CMathf::acos(-10.0), CMathf::PI));
$this->assertTrue(CMathf::equalsZt(CMathf::acos(0), 1.570796327));
}