A device for calculating exponential functions

摘要

1,113,699. Calculating device. W. F. BRAUN. 26 Aug., 1966 [2 Sept., 1965], No. 38364/66. Heading G4B. A device for calculating functions of the form and in particular for finding the exponent x given two pairs of values (P 0 , K 0 ), (P 1 , K 1 ), comprises two plates mounted in a frame, a first plate A carrying a logarithmic graph of the values of P and K, and the second plate B carrying a family of parallel straight lines. In a first embodiment, as shown, the plate A is movable such that the axes of the logarithmic graph remain parallel to their initial directions, while the plate B is rotatable about a point D of one of the family of straight lines. To perform a calculation the pairs of readings (P 0 , K,), (P 1 , K 1 ) are marked (1), (2) on the graph, and both plates are then moved until one of the straight lines passes through both marked points (1), (2). The slope of that line will then correspond to the value of the exponent x which may be read off from a scale X marked on the frame, and along this line new pairs of values (P, K) corresponding to the same exponent may be read off from the logarithmic graph. In a second embodiment (Figs. 2a and 2b, not shown), the plate A is fixed in the frame, while the plate B rotates about a plate (E) which is free to slide in a direction parallel to that of an axis of the graph of plate A, the plate (E) also carrying the exponent scale X. In a further embodiment (Fig. 3, not shown) tolerance limit lines are provided on plate B so that given one pair of readings (P 0 , K,) and a value for x, then tolerance limits for further pairs of values (P, K) may be found.