https://github.com/bilbottom/loan-calcs

Library for common loan calculations.
https://github.com/bilbottom/loan-calcs

Last synced: about 1 year ago
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Library for common loan calculations.

• Host: GitHub
• URL: https://github.com/bilbottom/loan-calcs
• Owner: Bilbottom
• Created: 2024-06-23T19:06:08.000Z (about 2 years ago)
• Default Branch: main
• Last Pushed: 2025-04-12T07:36:40.000Z (about 1 year ago)
• Last Synced: 2025-04-24T02:04:47.780Z (about 1 year ago)
• Language: Python
• Homepage:
• Size: 227 KB
• Stars: 0
• Watchers: 1
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Codeowners: .github/CODEOWNERS

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# Loan Calculations

Library for common loan calculations.

## Notation

A _loan_ is a fixed value of money borrowed by an entity and usually repaid over a series of instalments.

The following notation is used throughout this project for loans:

- `L`: Loan amount

- `R`: Periodic interest rate

- `N`: Total number of repayments

- `P_n`: Total periodic repayment value at period `n`

- `P_{P, n}`: The principal part of the periodic repayment value at period `n`

- `P_{I, n}`: The interest part of the periodic repayment value at period `n`

- `b`: Whether the interest is applied before or after the repayment

- `B_n`: The balance on the loan at period `n`

The repayment for a loan, `P_n`, is split into two parts:

- The _principal_ part, `P_{P, n}`, which is paying off the original money that was borrowed.

- The _interest_ part, `P_{I, n}`, which is paying off the interest applied on the loan.

In 'real life', a loan can have other components such as fees. These are outside the scope of this project.

## Calculations

Many of the properties are calculated analytically. The calculations are described in the [`tex/proofs.pdf`](tex/proofs.pdf) file.