Differential analyser

Common card · No. 481769

The differential analyser is a mechanical analogue computer designed to solve differential equations by integration, using wheel-and-disc mechanisms to perform the integration. It was one of the first advanced computing devices to be used operationally. In addition to the integrator devices, the machine used an epicyclic differential mechanism to perform addition or subtraction - similar to that used on a front-wheel drive car, where the speed of the two output shafts (driving the wheels) may differ but the speeds add up to the speed of the input shaft. Multiplication/division by integer values was achieved by simple gear ratios; multiplication by fractional values was achieved by means of a multiplier table, where a human operator would have to keep a stylus tracking the slope of a bar. A variant of this human-operated table was used to implement other functions such as polynomials.

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