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<?php |
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declare(strict_types = 1); |
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namespace ExtendedStrings\Strings; |
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class Harmonic |
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{ |
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private $halfStop; |
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private $baseStop; |
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/** |
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* Harmonic constructor. |
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* |
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* @param float $halfStop The string length of the harmonic-pressure stop. |
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* @param float $baseStop The string length of the base stop (defaults to |
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* 1.0, the open string). |
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*/ |
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public function __construct(float $halfStop, float $baseStop = 1.0) |
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{ |
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if ($halfStop > $baseStop) { |
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throw new \InvalidArgumentException("The half-stop's string length cannot be longer than the base stop's."); |
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} |
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$this->baseStop = $baseStop; |
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$this->halfStop = $halfStop; |
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} |
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/** |
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* Returns the sounding frequency of the harmonic, on a given string. |
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* |
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* @param \ExtendedStrings\Strings\VibratingString $string |
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* |
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* @return float |
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*/ |
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public function getSoundingFrequency(VibratingString $string): float |
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{ |
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// Transpose the half-stop onto the new string length, which was formed |
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// by the stop. |
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$pseudoString = new VibratingString($string->getStoppedFrequency($this->baseStop)); |
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$pseudoHalfStop = $this->halfStop / $this->baseStop; |
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return $pseudoString->getHarmonicSoundingFrequency($pseudoHalfStop); |
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} |
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/** |
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* Returns the string lengths that produce the given harmonic number. |
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* |
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* @param int $number The harmonic number. |
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* @param bool $exclusive When enabled, equivalent lengths will only be |
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* returned for the lowest harmonic number, e.g. the |
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* string length 0.5 will only be returned for |
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* harmonic 2 (not for harmonics 4, 6, 8, etc.). |
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* |
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* @return float[] |
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*/ |
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public static function getStringLengthsFromNumber(int $number, bool $exclusive = false): array |
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{ |
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$harmonics = []; |
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for ($numerator = 1; $numerator <= $number; $numerator++) { |
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if (!$exclusive || $numerator === 1 || (int) Math::gcd($numerator, $number) === 1) { |
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$harmonics[] = $numerator / $number; |
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} |
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} |
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return $harmonics; |
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} |
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/** |
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* Returns the harmonic series. |
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* |
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* @param int $limit |
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* |
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* @return float[] |
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*/ |
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public static function getSeries(int $limit): array |
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{ |
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$series = []; |
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$base = 0; |
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for ($denominator = 1; $denominator <= $limit; $denominator++) { |
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$base = $series[$denominator] = $base + 1 / $denominator; |
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} |
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return $series; |
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} |
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} |
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extended-strings /
strings
