Add bin and edit workflow

bin/gems/facets-3.1.0/lib/standard/facets/math/sign.rb

@@ -0,0 +1,20 @@
+module Math
+
+  # Sign of `x`. This function returns `-1.0` if `x` is negative,
+  # `+1.0` if `x` is positive `x`, and `0.0` if `x = 0`.
+  def self.sign(x, zero=0.0)
+    (x > 0.0) ? 1.0 : ((x < 0.0) ? -1.0 : zero)
+  end
+
+  # Same as `Math.sign`.
+  def self.sgn(x, zero=0.0)
+    (x > 0.0) ? 1.0 : ((x < 0.0) ? -1.0 : zero)
+  end
+
+  # The *Heaviside step function*, also called the the *unit step function*.
+  # This functions works like `Math.sign` but by default returns `1.0` for zero.
+  def self.unit_step(x, zero=1.0)
+    (x > 0.0) ? 1.0 : ((x < 0.0) ? -1.0 : zero)
+  end
+
+end