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ピアノの鍵盤の周波数を求める http://www.yamaha.co.jp/plus/piano/trivia/?ln=ja&id=103007
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' VBA | |
Private Const COMMON_RATIO As Double = 2 ^ (1 / 12) '1.0594630943592953... | |
Function calc_piano_frequency(Optional key_index As Integer = 49, Optional pitch As Integer = 440) As Double | |
Dim ratio As Double | |
ratio = COMMON_RATIO ^ (key_index - 49) | |
calc_piano_frequency = pitch * ratio | |
End Function | |
Sub exec_sample() | |
Debug.Print calc_piano_frequency | |
'=> 440 | |
Debug.Print calc_piano_frequency(1) | |
'=> 27.49999999999999 | |
Debug.Print calc_piano_frequency(88) | |
'=> 4186.009044809581 | |
End Sub |
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// JavaScript | |
const COMMON_RATIO = Math.pow(2, 1/12); //1.0594630943592953... | |
function calc_piano_frequency(key_index, pitch){ | |
if (key_index === undefined) key_index = 49; | |
if (pitch === undefined) pitch = 440; | |
var ratio = Math.pow(COMMON_RATIO, key_index - 49); | |
return pitch * ratio; | |
} | |
console.log(calc_piano_frequency()); | |
//=> 440 | |
console.log(calc_piano_frequency(1)); | |
//=> 27.49999999999999 | |
console.log(calc_piano_frequency(88)); | |
//=> 4186.009044809581 |
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# Ruby | |
COMMON_RATIO = 2 ** (1/12r) #1.0594630943592953... | |
def calc_piano_frequency(key_index = 49, pitch = 440) | |
ratio = COMMON_RATIO ** (key_index - 49) | |
pitch * ratio | |
end | |
puts calc_piano_frequency | |
#=> 440.0 | |
puts calc_piano_frequency 1 | |
#=> 27.499999999999947 | |
puts calc_piano_frequency 88 | |
#=> 4186.009044809585 |
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