public function spectrumWidth() {
		$spectrum = $this->spectrum();
		$output = array();
		foreach ($spectrum as $len => $spec) {
			$max = max($spec);
			$min = min($spec);
			$output[$len] = $max - $min;
		}
		return $output;
	}
public function spectrumWidth() {
		$spectrum = $this->spectrum();
		$output = array();
		foreach ($spectrum as $len => $spec) {
			$max = max($spec);
			$min = min($spec);
			$output[$len] = $max - $min;
		}
		return $output;
	}
public function spectrumWidth ( ) { $ spectrum = $ this -> spectrum ( ) ; $ output = array ( ) ; foreach ( $ spectrum as $ len => $ spec ) { $ max = max ( $ spec ) ; $ min = min ( $ spec ) ; $ output [ $ len ] = $ max - $ min ; } return $ output ; }
returns the spectrum widths for a PCS. Spectrum widths are used to calculate the "evenness" of pitch distribution.
The "spectrum width" is the difference between the largest and smallest member of the spectrum I.

In the literature, This width is notated as a "delta", ∆
So for example if the spectrum is
<1> = {1,3,4}
<2> = {4,5,6}
Then we would describe the spectrum widths thusly:
∆(1) = 3
∆(2) = 2
returns the spectrum widths for a PCS . Spectrum widths are used to calculate the evenness of pitch distribution . The spectrum width is the difference between the largest and smallest member of the spectrum I .