add modulus method to complex type

chippyash · Jul 26, 2014 · 3c6367b · 3c6367b
1 parent ee375b3
commit 3c6367b
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Showing 3 changed files with 46 additions and 1 deletion.
diff --git a/README.md b/README.md
@@ -151,9 +151,10 @@ Complex numbers support some additional attributes:
 *  isZero(): r() == i() == 0
 *  isGaussian(): is_int(r()) && is_int(i())
 
-and a method
+and two methods
 
 *  conjugate(): returns conjugate of the complex number
+*  modulus(): returns the modulus, also known as absolute value or magnitude of the complex number
 
 ### Changing the library
 
@@ -219,3 +220,5 @@ V1.0.1 Remove requirement for zendfilter package to reduce dependency footprint
 V1.0.2 Add conjugate method to complex type
 
        rebase wholeInt and naturalInt type on intType
+
+V1.0.3 Add modulus method to complex type
diff --git a/src/chippyash/Type/Number/Complex/ComplexType.php b/src/chippyash/Type/Number/Complex/ComplexType.php
@@ -90,6 +90,16 @@ public function conjugate()
         return new self(new FloatType($this->real), new FloatType($this->imaginary * -1));
     }
 
+    /**
+     * Return the modulus, also known as absolute value or magnitude of this number
+     * 
+     * @return \chippyash\Type\Number\FloatType
+     */
+    public function modulus()
+    {
+        return new FloatType(sqrt(pow($this->real, 2)+pow($this->imaginary, 2)));
+    }
+
     /**
      * Proxy to get()
      *

diff --git a/test/src/chippyash/Type/Number/Complex/ComplexTypeTest.php b/test/src/chippyash/Type/Number/Complex/ComplexTypeTest.php
@@ -148,4 +148,36 @@ public function testIsGaussianForOnePartNotBeingIntegerValuesReturnsFalse()
         $c2 = new ComplexType(new FloatType(1), new FloatType(2.000001));
         $this->assertFalse($c2->isGaussian());
     }
+
+    public function testModulusForZeroComplexNumberIsZero()
+    {
+        $c = new ComplexType(new FloatType(0), new FloatType(0));
+        $this->assertEquals(0, $c->modulus()->get());
+    }
+
+    public function testTriangleInequalityForModulus()
+    {
+        $c1 = new ComplexType(new FloatType(1), new FloatType(2));
+        $c2 = new ComplexType(new FloatType(3), new FloatType(4));
+        $c1addc2 = new ComplexType(new FloatType($c1->r() + $c2->r()), new FloatType($c1->i() + $c2->i()));
+        $mod1 = $c1->modulus();
+        $mod2 = $c2->modulus();
+        $modc1addc2 = $c1addc2->modulus();
+
+        $this->assertTrue($modc1addc2() <= ($mod1() + $mod2()));
+    }
+
+    public function testCommutativeMultiplicationAttributeForModulus()
+    {
+        $c1 = new ComplexType(new FloatType(1), new FloatType(2));
+        $c2 = new ComplexType(new FloatType(3), new FloatType(4));
+        $c1mulc2 = new ComplexType(
+                new FloatType(($c1->r() * $c2->r()) - ($c1->i() * $c2->i())),
+                new FloatType(($c1->i() * $c2->r()) + ($c1->r() * $c2->i())));
+        $mod1 = $c1->modulus();
+        $mod2 = $c2->modulus();
+        $modc1mulc2 = $c1mulc2->modulus();
+
+        $this->assertEquals($modc1mulc2(), $mod1() * $mod2());
+    }
 }