Bug #978: Range#step と Integer#step の振舞いの違い

• Status: Closed
• Assignee: -
• Target version: -

[tadf (tadayoshi funaba)]

=begin
以下のような場合に両者は等価に見えます。

0.step(10).to_a
#=> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

(0..10).step.to_a
#=> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

しかし、浮動小数点数をつかうと違いが見えます。

0.step(1,0.01).to_a
#=> [0.0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.7, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.8, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.0]

(0..1).step(0.01).to_a
#=> [0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.7, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.8, 0.81, 0.820000000000001, 0.830000000000001, 0.840000000000001, 0.850000000000001, 0.860000000000001, 0.870000000000001, 0.880000000000001, 0.890000000000001, 0.900000000000001, 0.910000000000001, 0.920000000000001, 0.930000000000001, 0.940000000000001, 0.950000000000001, 0.960000000000001, 0.970000000000001, 0.980000000000001, 0.990000000000001]

0.step(1,0.01).to_a.size
#=> 101

(0..1).step(0.01).to_a.size
#=> 100

おそらく、Integer#step に合せるべきです。
=end

[matz (Yukihiro Matsumoto)]

• Status changed from Open to Closed

=begin
fixed in r21298 and r21330.
=end