Nyholm\EffectiveInterest\Calculator

Complexity

Total Complexity

3

Size/Duplication

Total Lines	56
Duplicated Lines	10.71 %

Coupling/Cohesion

Components	1
Dependencies	1

Importance

Changes

0

3 Methods

Rating	Name	Duplication	Size	Complexity
A	__construct()	0	4	1
A	withSpecifiedPayments()	0	4	1
A	withEqualPayments()	6	12	1

<?php

namespace Nyholm\EffectiveInterest;

/**
 * @author Tobias Nyholm <tobias.nyholm@gmail.com>
 */
class Calculator
{
    /**
     * @var NewtonRaphson
     */
    private $newton;

    /**
     *
     * @param NewtonRaphson $newton
     */
    public function __construct(NewtonRaphson $newton = null)
    {
        $this->newton = $newton ?? new NewtonRaphson();
    }


    /**
     * Get the interest when you know all the payments and their dates. Use this function when you have
     * administration fees at the first payment and/or when payments are irregular.
     *
     * @param int    $principal
     * @param string $startDate in format 'YYYY-mm-dd'
     * @param array  $payments  array with payment dates and values ['YYYY-mm-dd'=>int]
     * @param float  $guess     A guess what the interest may be. Between zero and one. Example 0.045
     *
     * @return float
     */
    public function withSpecifiedPayments(int $principal, string $startDate, array $payments, float $guess): float

The parameter $principal is not used and could be removed.

The parameter $startDate is not used and could be removed.

The parameter $payments is not used and could be removed.

The parameter $guess is not used and could be removed.

    {
        return 0.045;
    }

    /**
     * Get the effective interest when the monthly payments are exactly the same.
     *
     * @param int   $a The total loan amount (Principal)
     * @param int   $p The monthly payment
     * @param int   $n The number of months
     * @param float $i A guess of what the interest might be. Interest as a number between zero and one. Example 0.045
     *
     * @return float
     */
    public function withEqualPayments(int $a, int $p, int $n, float $i): float
    {
        $fx = function ($i) use ($a, $p, $n) {

This code seems to be duplicated across your project.

            return  $p - $p * pow(1 + $i, -1 * $n) - $i * $a;
        };

        $fdx = function ($i) use ($a, $p, $n) {

This code seems to be duplicated across your project.

            return  $n * $p * pow(1 + $i, -1 * $n - 1) - $a;
        };

        return $this->newton->run($fx, $fdx, $i);
    }
}