public function testMagicProperty()
{
$annuityValueType = new AnnuityValueTypes(AnnuityValueTypes::FUTURE_VALUE);
// the enum's value should now be able to be channged by so much as assigning a magic property
// lets change it from the future value to present value and see if it comes through
$annuityValueType->magicProperty = AnnuityValueTypes::PRESENT_VALUE;
$this->assertEquals(AnnuityValueTypes::PRESENT_VALUE, $annuityValueType->getValue());
$this->assertEquals(AnnuityValueTypes::PRESENT_VALUE, $annuityValueType->magicProperty);
}
/**
* @param AnnuityPaymentTypes $annuityPaymentType
* @param AnnuityValueTypes $annuityValueType
* @return null|string
* @throws Exception
*/
public function getAnnuityValue(AnnuityPaymentTypes $annuityPaymentType = null, AnnuityValueTypes $annuityValueType)
{
// if the number of the annuity's compounding periods
// is set to zero, we're dealing with a perpetuity
if (Helpers::checkIfZero($this->annuityNoOfCompoundingPeriods)) {
// we cannot calculate FV of a perpetuity, we therefore return null
// in case such a value is demanded
if ($annuityValueType->getValue() == AnnuityValueTypes::FUTURE_VALUE) {
return null;
}
// PV of a perpetuity = K/i
return Helpers::roundMoneyForDisplay(MathFuncs::div($this->annuitySinglePaymentAmount, $this->annuityInterest));
}
// when the annuity is not a perpetuity, we first need to check that
// the $annuityPaymentType is not null
if (Helpers::checkIfNotNull($annuityPaymentType)) {
// discount factor 'v = 1/(1+i)'
$discountFactor = MathFuncs::div(1, MathFuncs::add(1, $this->annuityInterest));
if ($annuityValueType->getValue() == AnnuityValueTypes::PRESENT_VALUE) {
// PV numerator = 1-v^n
$numerator = MathFuncs::sub(1, MathFuncs::pow($discountFactor, $this->annuityNoOfCompoundingPeriods));
} elseif ($annuityValueType->getValue() == AnnuityValueTypes::FUTURE_VALUE) {
// FV numerator = (1+i)^n-1
$numerator = MathFuncs::sub(MathFuncs::pow(MathFuncs::add(1, $this->annuityInterest), $this->annuityNoOfCompoundingPeriods), 1);
}
if ($annuityPaymentType->getValue() == AnnuityPaymentTypes::IN_ADVANCE) {
// in advance denom. = 1-v
$denominator = MathFuncs::sub(1, $discountFactor);
} elseif ($annuityPaymentType->getValue() == AnnuityPaymentTypes::IN_ARREARS) {
// in arrears denom. = i
$denominator = $this->annuityInterest;
}
if (isset($numerator) && isset($denominator)) {
return MathFuncs::mul(MathFuncs::div($numerator, $denominator), $this->annuitySinglePaymentAmount);
}
}
return null;
}