From 559ebf200defaae65e53f3a7d97cc43d69209b8e Mon Sep 17 00:00:00 2001
From: Dennis Eichhorn <spl1nes.com@googlemail.com>
Date: Sat, 21 Sep 2019 15:26:53 +0200
Subject: [PATCH] fix docblock

---
 Math/Numerics/Integration.php                 | 150 ++++++++++++++++++
 .../CubicSplineInterpolation.php              |   2 +-
 .../Interpolation/LinearInterpolation.php     |   2 +-
 .../Interpolation/PolynomialInterpolation.php |   2 +-
 tests/Math/Numerics/IntegrationTest.php       |  65 ++++++++
 5 files changed, 218 insertions(+), 3 deletions(-)
 create mode 100644 Math/Numerics/Integration.php
 create mode 100644 tests/Math/Numerics/IntegrationTest.php

diff --git a/Math/Numerics/Integration.php b/Math/Numerics/Integration.php
new file mode 100644
index 000000000..155781897
--- /dev/null
+++ b/Math/Numerics/Integration.php
@@ -0,0 +1,150 @@
+<?php
+
+/**
+ * Orange Management
+ *
+ * PHP Version 7.4
+ *
+ * @package   phpOMS\Math\Numerics
+ * @copyright Dennis Eichhorn
+ * @license   OMS License 1.0
+ * @version   1.0.0
+ * @link      https://orange-management.org
+ */
+
+declare(strict_types=1);
+
+namespace phpOMS\Math\Numerics;
+
+/**
+ * Numerical integration.
+ *
+ * @package phpOMS\Math\Numerics
+ * @license OMS License 1.0
+ * @link    https://orange-management.org
+ * @since   1.0.0
+ */
+class Integration
+{
+    /**
+     * Integrate function by using rectangles from the left side
+     *
+     * @param float    $from Start interval
+     * @param float    $to   End interval
+     * @param float    $n    Steps
+     * @param \Closure $func Function to integrate
+     *
+     * @return float
+     *
+     * @since 1.0.0
+     */
+    public static function intLeftRect(float $from, float $to, float $n, \Closure $func) : float
+    {
+        $h   = ($to - $from) / $n;
+        $sum = 0.0;
+
+        for ($x = $from; $x <= ($to - $h); $x += $h) {
+            $sum += $func($x);
+        }
+
+        return $h * $sum;
+    }
+
+    /**
+     * Integrate function by using rectangles from the right side
+     *
+     * @param float    $from Start interval
+     * @param float    $to   End interval
+     * @param float    $n    Steps
+     * @param \Closure $func Function to integrate
+     *
+     * @return float
+     *
+     * @since 1.0.0
+     */
+    public static function intRightRect(float $from, float $to, float $n, \Closure $func): float
+    {
+        $h   = ($to - $from) / $n;
+        $sum = 0.0;
+
+        for ($x = $from; $x <= ($to - $h); $x += $h) {
+            $sum += $func($x + $h);
+        }
+
+        return $h * $sum;
+    }
+
+    /**
+     * Integrate function by using rectangles from a moving center point
+     *
+     * @param float    $from Start interval
+     * @param float    $to   End interval
+     * @param float    $n    Steps
+     * @param \Closure $func Function to integrate
+     *
+     * @return float
+     *
+     * @since 1.0.0
+     */
+    public static function intMiddleRect(float $from, float $to, float $n, \Closure $func): float
+    {
+        $h   = ($to - $from) / $n;
+        $sum = 0.0;
+
+        for ($x = $from; $x <= ($to - $h); $x += $h) {
+            $sum += $func($x + $h / 2.0);
+        }
+
+        return $h * $sum;
+    }
+
+    /**
+     * Integrate function by using trapezium
+     *
+     * @param float    $from Start interval
+     * @param float    $to   End interval
+     * @param float    $n    Steps
+     * @param \Closure $func Function to integrate
+     *
+     * @return float
+     *
+     * @since 1.0.0
+     */
+    public static function intTrapezium(float $from, float $to, float $n, \Closure $func): float
+    {
+        $h   = ($to - $from) / $n;
+        $sum = $func($from) + $func($to);
+
+        for ($i = 1; $i < $n; ++$i) {
+            $sum += 2 * $func($from + $i * $h);
+        }
+
+        return $h * $sum / 2.0;
+    }
+
+    /**
+     * Integrate by using the simpson rule
+     *
+     * @param float    $from Start interval
+     * @param float    $to   End interval
+     * @param float    $n    Steps
+     * @param \Closure $func Function to integrate
+     *
+     * @return float
+     *
+     * @since 1.0.0
+     */
+    public static function intSimpson(float $from, float $to, float $n, \Closure $func): float
+    {
+        $h    = ($to - $from) / $n;
+        $sum1 = 0.0;
+        $sum2 = 0.0;
+
+        for ($i = 1; $i < $n; ++$i) {
+            $sum1 += $func($from + $h * $i + $h / 2.0);
+            $sum2 += $func($from + $h * $i);
+        }
+
+        return $h / 6.0 * ($func($from) + $func($to) + 4.0 * $sum1 + 2.0 * $sum2);
+    }
+}
diff --git a/Math/Numerics/Interpolation/CubicSplineInterpolation.php b/Math/Numerics/Interpolation/CubicSplineInterpolation.php
index 18078c0d2..200303bed 100644
--- a/Math/Numerics/Interpolation/CubicSplineInterpolation.php
+++ b/Math/Numerics/Interpolation/CubicSplineInterpolation.php
@@ -15,7 +15,7 @@ declare(strict_types=1);
 namespace phpOMS\Math\Numerics\Interpolation;
 
 /**
- * Web module interface.
+ * Cubic spline interpolation.
  *
  * @package phpOMS\Math\Numerics\Interpolation
  * @license OMS License 1.0
diff --git a/Math/Numerics/Interpolation/LinearInterpolation.php b/Math/Numerics/Interpolation/LinearInterpolation.php
index 640c0b83b..c8231454f 100644
--- a/Math/Numerics/Interpolation/LinearInterpolation.php
+++ b/Math/Numerics/Interpolation/LinearInterpolation.php
@@ -15,7 +15,7 @@ declare(strict_types=1);
 namespace phpOMS\Math\Numerics\Interpolation;
 
 /**
- * Web module interface.
+ * Linear spline interpolation.
  *
  * @package phpOMS\Math\Numerics\Interpolation
  * @license OMS License 1.0
diff --git a/Math/Numerics/Interpolation/PolynomialInterpolation.php b/Math/Numerics/Interpolation/PolynomialInterpolation.php
index 970c730f5..b0b574baa 100644
--- a/Math/Numerics/Interpolation/PolynomialInterpolation.php
+++ b/Math/Numerics/Interpolation/PolynomialInterpolation.php
@@ -15,7 +15,7 @@ declare(strict_types=1);
 namespace phpOMS\Math\Numerics\Interpolation;
 
 /**
- * Web module interface.
+ * Polynomial spline interpolation.
  *
  * @package phpOMS\Math\Numerics\Interpolation
  * @license OMS License 1.0
diff --git a/tests/Math/Numerics/IntegrationTest.php b/tests/Math/Numerics/IntegrationTest.php
new file mode 100644
index 000000000..77761ce32
--- /dev/null
+++ b/tests/Math/Numerics/IntegrationTest.php
@@ -0,0 +1,65 @@
+<?php
+
+/**
+ * Orange Management
+ *
+ * PHP Version 7.4
+ *
+ * @package   tests
+ * @copyright Dennis Eichhorn
+ * @license   OMS License 1.0
+ * @version   1.0.0
+ * @link      https://orange-management.org
+ */
+
+declare(strict_types=1);
+
+namespace phpOMS\tests\Math\Numerics;
+
+use phpOMS\Math\Numerics\Integration;
+
+/**
+ * @internal
+ */
+class IntegrationTest extends \PHPUnit\Framework\TestCase
+{
+    public function testLRect(): void
+    {
+        self::assertEqualsWithDelta(0.235322, Integration::intLeftRect(0.0, 1.0, 100.0, function($x) { return $x**3; }), 0.001);
+        self::assertEqualsWithDelta(4.654000, Integration::intLeftRect(1.0, 100.0, 1000.0, function($x) { return 1 / $x; }), 0.001);
+        self::assertEqualsWithDelta(12499992.500730, Integration::intLeftRect(0.0, 5000.0, 5000000.0, function($x) { return $x; }), 0.001);
+        self::assertEqualsWithDelta(17999991.001392, Integration::intLeftRect(0.0, 6000.0, 6000000.0, function($x) { return $x; }), 0.001);
+    }
+
+    public function testRRect(): void
+    {
+        self::assertEqualsWithDelta(0.245025, Integration::intRightRect(0.0, 1.0, 100.0, function($x) { return $x**3; }), 0.001);
+        self::assertEqualsWithDelta(4.555991, Integration::intRightRect(1.0, 100.0, 1000.0, function($x) { return 1 / $x; }), 0.001);
+        self::assertEqualsWithDelta(12499997.500729, Integration::intRightRect(0.0, 5000.0, 5000000.0, function($x) { return $x; }), 0.001);
+        self::assertEqualsWithDelta(17999997.001390, Integration::intRightRect(0.0, 6000.0, 6000000.0, function($x) { return $x; }), 0.001);
+    }
+
+    public function testMRect(): void
+    {
+        self::assertEqualsWithDelta(0.240137, Integration::intMiddleRect(0.0, 1.0, 100.0, function($x) { return $x**3; }), 0.001);
+        self::assertEqualsWithDelta(4.603772, Integration::intMiddleRect(1.0, 100.0, 1000.0, function($x) { return 1 / $x; }), 0.001);
+        self::assertEqualsWithDelta(12499995.000729, Integration::intMiddleRect(0.0, 5000.0, 5000000.0, function($x) { return $x; }), 0.001);
+        self::assertEqualsWithDelta(17999994.001391, Integration::intMiddleRect(0.0, 6000.0, 6000000.0, function($x) { return $x; }), 0.001);
+    }
+
+    public function testTrapeze(): void
+    {
+        self::assertEqualsWithDelta(0.250025, Integration::intTrapezium(0.0, 1.0, 100.0, function($x) { return $x**3; }), 0.001);
+        self::assertEqualsWithDelta(4.605986, Integration::intTrapezium(1.0, 100.0, 1000.0, function($x) { return 1 / $x; }), 0.001);
+        self::assertEqualsWithDelta(12500000.0, Integration::intTrapezium(0.0, 5000.0, 5000000.0, function($x) { return $x; }), 0.001);
+        self::assertEqualsWithDelta(18000000.0, Integration::intTrapezium(0.0, 6000.0, 6000000.0, function($x) { return $x; }), 0.001);
+    }
+
+    public function testSimpson(): void
+    {
+        self::assertEqualsWithDelta(0.25, Integration::intSimpson(0.0, 1.0, 100.0, function ($x) { return $x ** 3; }), 0.001);
+        self::assertEqualsWithDelta(4.605170, Integration::intSimpson(1.0, 100.0, 1000.0, function ($x) { return 1 / $x; }), 0.001);
+        self::assertEqualsWithDelta(12500000.0, Integration::intSimpson(0.0, 5000.0, 5000000.0, function ($x) { return $x; }), 0.001);
+        self::assertEqualsWithDelta(18000000.0, Integration::intSimpson(0.0, 6000.0, 6000000.0, function ($x) { return $x; }), 0.001);
+    }
+}