Inexactness and a future of computing.

As pressures, notably from energy consumption, start impeding the growth and scale of computing systems, inevitably, designers and users are increasingly considering the prospect of trading accuracy or exactness. This paper is a perspective on the progress in embracing this somewhat unusual philosophy of innovating computing systems that are designed to be inexact or approximate, in the interests of realizing extreme efficiencies. With our own experience in designing inexact physical systems including hardware as a backdrop, we speculate on the rich potential for considering inexactness as a broad emerging theme if not an entire domain for investigation for exciting research and innovation. If this emerging trend to pursuing inexactness persists and grows, then we anticipate an increasing need to consider system co-design where application domain characteristics and technology features interplay in an active manner. A noteworthy early example of this approach is our own excursion into tailoring and hence co-designing floating point arithmetic units guided by the needs of stochastic climate models. This approach requires a unified effort between software and hardware designers that does away with the normal clean abstraction layers between the two.