# finance 0.1.0

The fundamental package for financial computing with Dart.

The fundamental package for financial computing with Dart.

This package provides a set of high-level functions and classes that make it easy to compute financial ratios, patterned after spreadsheet computations. It's platform-independent, supports iOS and Android.

# Using #

The easiest way to use this library is via the top-level functions. They allow you to make financial calculations with minimal hassle:

## Future Value calculation #

What is the future value after 30 years of saving $1000 now, with an additional monthly savings of $100. Assume the interest rate is 7% (annually) compounded monthly?

```
print(Finance.fv(rate: 0.07 / 12, nper: 30 * 12, pmt: -100, pv: -1000));
```

Thus, saving $1000 today and then $100 a month at 7% annual interest leads to $130,113.59 available to spend in 30 years from now.

## Payments calculation #

What is the monthly payment needed to pay off a $100,000 loan in 10 years at an annual interest rate of 2.5%?

```
print(Finance.pmt(rate: 0.025 / 12, nper: 10 * 12, pv: 100000));
```

Thus, in order to pay-off (i.e., have a future-value of 0) the $100,000 obtained today, a monthly payment of $942.69 would be required. Note that this example illustrates usage of future value having a default value of 0.

## Number of period calculation #

If we only had $500/month to pay towards the loan, how long would it take to pay-off a loan of $100,000 at 3% annual interest?

```
print(Finance.nper(rate: 0.03 / 12, pmt: -500, pv: 10000));
```

So, over 20 months would be required to pay off the loan.

## Principal and Interest payment calculation #

What is the amortization schedule for a 1 year loan of $5000 at 10% interest per year compounded monthly? And the total interest payments?

```
final Iterable<Map<String, num>> payments =
List<int>.generate(12, (int index) => index + 1).map((int per) =>
<String, num>{
'per': per,
'pmt': Finance.pmt(rate: 0.1 / 12, nper: 1 * 12, pv: 5000),
'ppmt':
Finance.ppmt(rate: 0.1 / 12, per: per, nper: 1 * 12, pv: 5000),
'ipmt':
Finance.ipmt(rate: 0.1 / 12, per: per, nper: 1 * 12, pv: 5000),
});
payments.forEach(print);
final num interestPaid =
payments.fold(0, (num p, Map<String, num> c) => p + c['ipmt']);
print(interestPaid);
```

Thus, the total interest paid are close to $275.

## Present Value calculation #

What is the present value (e.g., the initial investment) of an investment that needs to total $20,000 after 10 years of saving $100 every month? Assume the interest rate is 7% (annually) compounded monthly.

```
print(Finance.pv(rate: 0.05 / 12, nper: 10 * 12, pmt: -100, fv: 15692.93));
```

So, to end up with $20,000 in 10 years saving $100 a month at 7% annual interest, one's initial deposit should be $1,339.28.

## Interest rate calculation #

What is the interest rate for a $8,000 loan if the loan term is 5 years and and payments are $152.50 monthly?

```
print(Finance.rate(nper: 60, pmt: -152.5, pv: 8000, fv: 0));
```

The calculated interest rate is 0.45% monthly, or 5.42% annually.

## Net present value calculation #

What is the Net Present Value of an investment that requires $15000 deposit now and then makes the following withdrawals at regular (fixed) intervals: 1500, 2500, 3500, 4500, 6000?. Assuming the ending value is 0 and a discount rate of 5%.

```
print(Finance.npv(rate: 0.05, values: <num>[-15000, 1500, 2500, 3500, 4500, 6000]));
```

So, this investment is worth $122.894 today.

## Internal Rate of Return calculation #

What is the Internal Rate of return of an investment that requires $15000 deposit now and then makes the following withdrawals at regular (fixed) intervals: 1500, 2500, 3500, 4500, 6000?. Assuming the ending value is 0.

```
print(Finance.irr(rate: 0.05, values: <num>[-15000, 1500, 2500, 3500, 4500, 6000]));
```

So, the IRR of this investment is 5.24%.