internal static double IntTimesPeriod(double intTimes, InterestPeriods iPeriods) // if interest is not accounted Annually.
{
switch (iPeriods)
{
case InterestPeriods.Daily:
return(365 / intTimes);
case InterestPeriods.Weekly:
return(52 / intTimes);
case InterestPeriods.Monthly:
return(12 / intTimes);
default:
return(1);
}
}
public static string Calculate(decimal interestRate, double intTimes, InterestPeriods iPeriods)
{
try
{
decimal eir = (((decimal)Pow((double)(1 + (interestRate / 100) / (decimal)IntTimesPeriod(intTimes, iPeriods)), IntTimesPeriod(intTimes, iPeriods))) - 1) * 100;
eir = Round(eir, 2);
return($"Effective Interest Rate: {eir}%\n" +
"Used formula: [(1 + r%/m)^m-1] × 100\n" +
$"Solution: [(1 + {interestRate / 100}/{IntTimesPeriod(intTimes, iPeriods)})^{IntTimesPeriod(intTimes, iPeriods)}-1] × 100 = {eir}%");
}
catch (OverflowException)
{
return("Impossible Calculation!");
}
catch (DivideByZeroException)
{
return("Dividing by zero error!\n" +
"Please check your input.\n" +
"If your input is correct and you get this error, then your calculation is impossible.");
}
}
public static string CDiscursiveInterest(decimal presentValue, decimal interestRate, double period, double intTimes, InterestPeriods iPeriods) // if interest is not accounted Annually
{
try
{
decimal futureValue = presentValue * (decimal)Pow((double)(1 + ((interestRate / 100) / (decimal)IntTimesPeriod(intTimes, iPeriods))), period * IntTimesPeriod(intTimes, iPeriods));
futureValue = Round(futureValue, 2);
return($"Future Value: {futureValue:C2}\n" +
"Used formula: FV = PV × (1 + r%/m)^(m × n)\n" +
$"Solution: {presentValue} × (1 + {interestRate / 100}/{IntTimesPeriod(intTimes, iPeriods)})^({period} × {IntTimesPeriod(intTimes, iPeriods)}) = {futureValue:0.00}");
}
catch (OverflowException)
{
return("Impossible Calculation!");
}
catch (DivideByZeroException)
{
return("Dividing by zero error!\n" +
"Please check your input.\n" +
"If your input is correct and you get this error, then your calculation is impossible.");
}
}
