Exploiting Errors for Efficiency: A Survey from Circuits to Algorithms <s> Analog computing: data processing with currents and voltages <s> By Walter J. Karplus and Walter W. Soroka London: McGraw-Hill Publishing Co. Ltd. Pp. xiii + 483. Price 97s. This is the second edition of a previous book with the same title by Soroka alone. Like its predecessor, it offers a comprehensive treatment of analogue methods and techniques, the main difference being that the emphasis has been shifted from mechanical to electrical and electronic equipment in keeping with the times. <s> BIB001 </s> Exploiting Errors for Efficiency: A Survey from Circuits to Algorithms <s> Analog computing: data processing with currents and voltages <s> We review the pros and cons of analog and digital computation. We propose that computation that is most efficient in its use of resources is neither analog computation nor digital computation but, rather, a mixture of the two forms. For maximum efficiency, the information and informationprocessing resources of the hybrid form must be distributed over many wires, with an optimal signal-to-noise ratio per wire. Our results suggest that it is likely that the brain computes in a hybrid fashion and that an underappreciated and important reason for the efficiency of the human brain, which consumes only 12 W, is the hybrid and distributed nature of its architecture. <s> BIB002
Analog computing systems BIB001  eliminate the need for discretization and the resulting restriction on precision that is inherent in digital circuits. While, in theory, analog circuits provide unbounded precision, in practice their precision is limited by factors such as noise, non-linearities, the degree of control of properties of circuit elements such as resistors and capacitors, and the degree of control of implicit parameters such as temperature. At higher precision, analog blocks tend to be less energy-efficient than digital blocks of equivalent precision BIB002 . Because they usually do not use minimum-size transistors, analog circuits may also be larger in area than their digital circuit equivalents. Designing analog computation units is also a challenging task. Nevertheless, analog circuits can be an attractive solution for applications that tolerate low-precision computation BIB002 .