REM  *****  BASIC  *****


Function  present_value ( initial_value As  Double, annual_rate As Double, number_of_years As Double, monthly_payments As Double )  As  Double

	v0 = initial_value
	r  = 1 +  annual_rate/12
	n  = number_of_years * 12
	p  = monthly_payments
	
	if (1-r) = 0 then
		present_value = -77777
	else
		present_value  = v0*r^n - p * (1-r^n)/(1-r)
	endif
	
End Function


Function  default_payment ( initial_value As  Double, annual_rate As Double, number_of_years As Double )  As  Double

	v0 = initial_value
	v  = 0
	r  = 1 +  annual_rate/12
	n  = number_of_years * 12
	
	if r = 1 then
		default_payment = 77777
	else
	 	default_payment  = (v0*r^n - v)*(1-r)/(1-r^n)
	endif

End Function

Function  payoff_period ( initial_value As  Double, annual_rate As Double,  monthly_payments As Double )  As  Double

	v0 = initial_value
	v  = 0
	r  = 1 +  annual_rate/12
	p  = monthly_payments
	pr = p / (1 - r)
	
	if r = 1 or (v0 + pr) = 0 then
		payoff_period  = 77777
	else
		payoff_period  = Log( (v + pr) / (v0 + pr) ) / Log(r) / 12
	endif

End Function