Created
February 21, 2013 08:42
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Ruby script to definite integral by simpson method.
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# -*- coding: utf-8 -*- | |
#********************************************* | |
# シンプソン則による定積分 | |
#********************************************* | |
class DefiniteIntegralSimpson | |
# 積分区間分割数 | |
M = 100 | |
# 計算クラス | |
class Calc | |
# 被積分関数 | |
def f(x) | |
return Math.sqrt(4 - x * x) | |
end | |
# 定積分計算 | |
def generate_integral(a, b) | |
# 1区間の幅 | |
h = (b - a) / (2 * M).to_f | |
# 初期化 | |
x = a # X 値を a で初期化 | |
f_o = 0 # 奇数項の合計 | |
f_e = 0 # 偶数項の合計 | |
# 奇数項の合計、偶数項の合計計算 | |
1.upto(2 * M - 2) do |k| | |
x += h | |
if k % 2 == 1 | |
f_o += f(x) | |
else | |
f_e += f(x) | |
end | |
end | |
# 面積計算 | |
s = f(a) + f(b) | |
s += 4 * (f_o + f(b-h)) + 2 * f_e | |
s *= h / 3.0 | |
# 結果表示 | |
printf(" /%f\n",b); | |
printf(" | f(x)dx = %f\n", s); | |
printf(" /%f\n",a); | |
end | |
end | |
# メイン処理 | |
begin | |
# データ入力 | |
print "積分区間 A :" | |
a = gets.chomp.to_f | |
print " B :" | |
b = gets.chomp.to_f | |
exit if a == 0 && b == 0 | |
# 計算クラスインスタンス化 | |
obj_calc = Calc.new | |
# 定積分計算 | |
obj_calc.generate_integral(a, b) | |
rescue => e | |
# エラーメッセージ | |
puts "[例外発生] #{e}" | |
end | |
end |
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