第2回 Inharmonicity #2

Octaveの実行画面で キー番号と弦長と番手（又は弦径）を入力すると

>> getInha(49, 390, 16.5)
ans = 0.66496

結果が表示されます。

function inh = getInha(key, leng, ban)
  me = 1000;
  cm = 10;
  [di, pitch] = getDia(ban);

  inh = 3.3*cm^13*(di/cm)^2/(leng/cm)^4/getFreq(key, pitch)^2;
end

function [dia, aa] = getDia(bante)
  ba = 12:0.5:25;
  dm = 1.25:0.05:1.500;
  da = 0.725:0.025:1.225;
  di = [da dm];

  dia = -1;
  aa = 440;

  if (bante < 12 && bante > 0.1)
    dia = bante;
    aa = 415;
  else
    x = find(ba == bante);
    if (x > 0)
      dia = di(x);
    end
  end
end # 番手から弦径とピッチを得ます

function freq = getFreq(key, pitch)
  freq = pitch .* 2.^((key-49)./12);
end # キー番号から周波数を算出します