APRC Solver

Licence: GNU GENERAL PUBLIC LICENSE (see LICENCE document) - No liability of usage

Author: Olafur Orn Gudmundsson

NPM package: https://www.npmjs.com/package/aprc-solver

About APRC Solver

APRC solver solves APRC out of the APRC formula (i.e. the X variable)

by using binary search. This solver assumes that all the loan is paid out in the beginning of the loan time so the formula can be simplified into:

Usage

Example of usage

import { calcAprc } from 'aprc-solver'

const monthlyPayments = [110, 107, 105, 102];
const s = 380; // user gets 380 money into his pocket

const aprc = calcAprc(monthlyPayments, s)

Details

We use trial and error with binary search to find APRC, similar to the Goal Seek function in Excel. See formula for APRC: https://www.handbook.fca.org.uk/handbook/MCOB/10A/2.html?date=2016-06-30 The formula assumes that there is monthly payments and the first payment is 1 month after loan is taken. It also assumes that every month in the year has equal length.

ATTRIBUTES: @param payments: List of all the repayments back to loan provider. @param s: The s variable in the APRC formula. The money which the person gets in his pocket when taking the loan

@return value between 0 and 1 (the APRC) rounded to the fourth decimal place

Inspiration

An APRC solver was needed for the consumer loans comparison on Aurbjörg.is and it wasn't possible to find open source NPM package to calculate APRC from the APRC formula.

This package is published to increase transparency for the calculation on Aurbjörg.is and for other to use as open source code to solve APRC is lacking.