An instance of both unary function and evaluatable function. When applied to an instance SCALAR of quantity, inverse returns an instance RECIPROCAL of quantity that is the reciprocal of SCALAR. If SCALAR is an instance of scalar value, then RECIPROCAL is an instance of scalar value whose product (see Times Fn) with SCALAR is 1. For instance, (inverse 2) is 0.5 and (inverse (meter 2)) is ((Per Fn unity meter) 0.5), a quantity whose product with (meter 2) is 1. If SCALAR is a range of values (rather than an instance of scalar value), then RECIPROCAL is also a range of values, with the reciprocal of the maximum value of SCALAR serving as RECIPROCAL's minimum value, and the reciprocal of the minimum value of SCALAR serving as RECIPROCAL's maximum value. For example, (inverse (unity 1 2)) (i.e., the reciprocal of the range of numbers from 1 to 2) is (unity 0.5 1). Note that when SCALAR and RECIPROCAL are ranges of values, the product of SCALAR and RECIPROCAL may not be 1; for example, the product of (inverse (unity 1 2)) and (unity 1 2) is (unity 0.5 2). Nevertheless, even when the product of SCALAR and RECIPROCAL is not 1, 1 will lie within the range (see Value In Range) of the product of SCALAR and RECIPROCAL. Finally, note that (inverse 0) is undefined.