Taylor series expansion of a function is an approximation of a differentiable function as an infinite sum of derivatives at a given point. The Wikipedia article defines it as
By change of variables, [math] and [math], the Taylor series can be rewritten as
Each derivative quantity above has its own unique unit of measure. Keeping track of the measure is essential to computing the final estimate. The example below shows how the measures are defined, multiplied, summed, and simplified.