bye static methods, you just make things more difficult

README.md

@@ -25,21 +25,14 @@ $ema = new Romulodl\Ema();
 $ema->calculate([10, 12, 14, 20, 14, 10, 11]);
 ```
 
-it also contains a static method:
-
-```php
-Ema::calculateStatic([10, 12, 14, 20, 14, 10, 11]);
-```
-
 #### What is `$previous_values` for?
 
-The EMA calculation is based on the previous round of calculation. So the n round depends on n - 1 results.
-Then what is n - 1 for the first calculation? If `$previous_values` is not available, it uses a simple moving average
+The EMA calculation is based on the previous round of calculation. The `n` round depends on `n - 1` result.
+Then what is `n - 1` for the first round? If `$previous_values` is not available, it uses a simple moving average
 for it. With `$previous_values` set, it will start the calculation of the EMA before and the result will be more
-accurate (at least closest to what Trading view shows.)
-
+accurate (at least closest to what TradingView shows.)
 
 ## Why did you do this?
 
 The PECL Trading extension is crap and not everyone wants to install it.
-I am building a trading bot and building more complex trading indicators that use EMA as a basic step.
+I am building a trading bot and building more complex trading indicators that use the EMA as a basic step.

src/Ema.php

@@ -4,50 +4,51 @@
 
 class Ema
 {
-	private static $mult = null;
-
-	public function calculate(array $values, array $previous_values = []) : float
-	{
-		return self::calculate_ema($values, $previous_values);
-	}
-
-	public static function calculateStatic(array $values, array $previous_values = []): float
-	{
-		return self::calculate_ema($values, $previous_values);
-	}
-
 	/**
 	 * Calculate the EMA based on this formula
 	 * (Close - previous EMA) * (2 / n+1) + previous EMA
 	 *
 	 * The previous values options exists to try to smooth the current calculation
 	 * if it is empty, it will calculate the SMA for the first round.
 	 */
-	private static function calculate_ema(array $values, array $previous_values = []) : float
+	public function calculate(array $values, array $previous_values = []) : float
 	{
 		if (empty($values)) {
 			throw new \Exception('[' . __METHOD__ . '] $values parameters is empty');
 		}
 
-		self::$mult = self::$mult ?: 2 / (count($values) + 1);
-		$prev = false;
+		$mult = 2 / (count($values) + 1);
+
+		return $this->calculate_ema($values, $mult, $previous_values);
+	}
+
+	private function calculate_ema(
+		array $values,
+		float $mult,
+		array $previous_values = [],
+		$prev = false
+	): float
+	{
 		foreach ($values as $value) {
 			if ( !is_numeric($value)) {
 				throw new \Exception('[' . __METHOD__ . '] invalid value: '. $value);
 			}
 
 			if (!$prev) {
-				$prev = !empty($previous_values) ? self::calculate_ema($previous_values) : self::sma($values);
+				$prev = !empty($previous_values) ?
+					$this->calculate_ema($previous_values, $mult) :
+					$this->sma($values);
+
 				continue;
 			}
 
-			$prev = ($value - $prev) * self::$mult + $prev;
+			$prev = ($value - $prev) * $mult + $prev;
 		}
 
-		return $prev ?: 0;
+		return $prev;
 	}
 
-	private static function sma(array $values) : float
+	private function sma(array $values) : float
 	{
 		return array_sum($values) / count($values);
 	}

tests/TestEma.php

@@ -23,7 +23,6 @@ public function testCalculateEmaWithEmptyPreviousValues(): void
 
 		$ema = new Ema();
 		$this->assertSame(9288.86, round($ema->calculate($values), 2));
-		$this->assertSame(9288.86, round(Ema::calculateStatic($values), 2));
 	}
 
 	public function testCalculateEmaWithPreviousValues(): void
@@ -56,7 +55,6 @@ public function testCalculateEmaWithPreviousValues(): void
 
 		$ema = new Ema();
 		$this->assertSame(9197.01, round($ema->calculate($values, $previous_values), 2));
-		$this->assertSame(9197.01, round(Ema::calculateStatic($values, $previous_values), 2));
 	}
 
 	public function testCalculateEmaWithMorePreviousValues(): void
@@ -92,7 +90,6 @@ public function testCalculateEmaWithMorePreviousValues(): void
 
 		$ema = new Ema();
 		$this->assertSame(9182.18, round($ema->calculate($values, $previous_values), 2));
-		$this->assertSame(9182.18, round(Ema::calculateStatic($values, $previous_values), 2));
 	}
 
 	public function testCalculateEmaWithEmptyArray(): void
@@ -101,13 +98,6 @@ public function testCalculateEmaWithEmptyArray(): void
 
 		$ema = new Ema();
 		$ema->calculate([]);
-		Ema::calculateStatic([]);
-	}
-
-	public function testCalculateStaticEmaWithEmptyArray(): void
-	{
-		$this->expectException(Exception::class);
-		Ema::calculateStatic([]);
 	}
 
 	public function testCalculateEmaWithInvalidArray(): void
@@ -129,26 +119,5 @@ public function testCalculateEmaWithInvalidArray(): void
 
 		$ema = new Ema();
 		$ema->calculate($values);
-		Ema::calculateStatic($values);
-	}
-
-	public function testCalculateEmaStaticWithInvalidArray(): void
-	{
-		$values = [
-			9148.27,
-			9995,
-			9807.49,
-			'hahah',
-			8719.53,
-			8561.09,
-			8808.71,
-			9305.91,
-			9786.80,
-			9310.73
-		];
-
-		$this->expectException(Exception::class);
-
-		Ema::calculateStatic($values);
 	}
 }