Data commit

Task/Approximate-equality/Ruby/approximate-equality.rb

@@ -0,0 +1,27 @@
+require "bigdecimal"
+
+testvalues = [[100000000000000.01,           100000000000000.011],
+              [100.01,                       100.011],
+              [10000000000000.001 / 10000.0, 1000000000.0000001000],
+              [0.001,                        0.0010000001],
+              [0.000000000000000000000101,   0.0],
+              [(2**0.5) * (2**0.5),            2.0],
+              [-(2**0.5) * (2**0.5),          -2.0],
+              [BigDecimal("3.14159265358979323846"),       3.14159265358979324],
+              [Float::NAN, Float::NAN,],
+              [Float::INFINITY, Float::INFINITY],
+               ]
+
+class  Numeric
+  def close_to?(num, tol = Float::EPSILON)
+    return true  if self == num
+    return false if (self.to_f.nan? or num.to_f.nan?)        # NaN is not even close to itself
+    return false if [self, num].count( Float::INFINITY) == 1 # Infinity is only close to itself
+    return false if [self, num].count(-Float::INFINITY) == 1
+    (self-num).abs <= tol * ([self.abs, num.abs].max)
+  end
+end
+
+testvalues.each do |a,b|
+  puts "#{a} #{a.close_to?(b) ? '≈' : '≉'} #{b}"
+end