Parallel (operator)

The parallel operator ∥ (pronounced "parallel") is a mathematical function which is used especially as shorthand in electrical engineering. It represents the reciprocal value of a sum of reciprocal values and is defined by:

∥ :   C ¯ × C ¯ → C ¯ ( a , b ) ↦ a ∥ b = 1 1 a + 1 b

That is, it gives half of the harmonic mean of two numbers a and b.