finance_rb

This package is a ruby native port of the numpy-financial package with some helpful additional functions.

The functions in this package are a scalar version of their vectorised counterparts in the numpy-financial library.

Currently, only some functions are ported,
which are as follows:

numpy-financial function	ruby native function ported?	info
fv	✅	Computes the future value
ipmt	✅	Computes interest payment for a loan
pmt	✅	Computes the fixed periodic payment(principal + interest) made against a loan amount
ppmt	✅	Computes principal payment for a loan
nper	✅	Computes the number of periodic payments
pv	✅	Computes the present value of a payment
rate	✅	Computes the rate of interest per period
irr	✅	Computes the internal rate of return
npv	✅	Computes the net present value of a series of cash flow
mirr	✅	Computes the modified internal rate of return

Things to be done:

1. Xirr
2. More specs for edge cases
3. Fee, currency protection and other cool stuff for advanced usage
4. Better errors
5. A detailed documentation for all methods

Documentation

Detailed documentation is available at rubydoc.

Basic usage

There is no need to create a loan class to calculate some basic functions, such as npv, irr, or mirr. Simply call a needed method with required arguments using calculations class.

1. IRR (Internal Rate of Return)

   Finance::Calculations.irr([-4000,1200,1410,1875,1050])
   => 0.14299344106053188

2. MIRR (Modified Internal Rate of Return)

   Finance::Calculations.mirr([100, 200, -50, 300, -200], 0.05, 0.06)
   => 0.3428233878421769

3. NPV (Net Present Value)

   Finance::Calculations.net_present_value(0.1, [-100, 6, 6, 6])
   => -85.07888805409468

Advanced Usage

Create a loan instance, and pass available parameters for nominal annual rate, duration (in months), and amount of loan.

loan = Finance::Loan.new(nominal_rate: 0.1, duration: 12, amount: 1000)
loan.pmt # => -87.9158872300099

Available methods: pmt, ipmt, ppmt, nper, pv, fv, rate.

Installation

finance_rb is available as a gem, to install it just install the gem:

gem install finance_rb

If you're using Bundler, add the gem to Gemfile.

gem 'finance_rb'

Run bundle install.

Running tests

bundle exec rspec spec/

Available Functions

** Simple financial functions **

• fv(rate, nper, pmt, pv[, when]) Compute the future value.
• pv(rate, nper, pmt[, fv, when]) Compute the present value.
• npv(rate, values) Returns the NPV (Net Present Value) of a cash flow series.
• pmt(rate, nper, pv[, fv, when]) Compute the payment against loan principal plus interest.
• ppmt(rate, per, nper, pv[, fv, when]) Compute the payment against loan principal.
• ipmt(rate, per, nper, pv[, fv, when]) Compute the interest portion of a payment.
• irr(values) Return the Internal Rate of Return (IRR).
• mirr(values, finance_rate, reinvest_rate) Modified internal rate of return.
• nper(rate, pmt, pv[, fv, when]) Compute the number of periodic payments.
• nrate(nper, pmt, pv, fv[, when, guess, tol, …]) Compute the rate of interest per period.

Contributing

1. Fork it ( https://github.com/wowinter13/finance_rb/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

License

MIT License. See LICENSE for details.