GB1151302A - Improvements in and relating to Computer Equipment for Numerical Solution of Complex Number Problems - Google Patents

Abstract

1,151,302. Combined digital analogue computer. TESLA, NARODNI PODNIK. 18 May, 1967, No. 23041/67. Headings G4A and G4G. Computer equipment for solving complex number calculations comprises an analogue unit, a digital unit and linkages therebetween, whereby electric signals corresponding to the absolute values of the real and imaginary parts of the complex numbers are fed to the analogue unit and the signals of the plus and minus signs are fed to the digital unit and by means of an analogue-to-digital linkage the signals are transferred to determine the final sign of the result and the signals of the analogue and digital units are brought to an evaluation unit which indicates the desired result. If two numbers k 1 a +jk 2 b and k 3 c +jk 4 d are to be multiplied, where k 1 -k 4 are the plus or minus signs, to produce a result m(ac+nbd)+ jp(ad+rbc, where m, n, p, r are plus or minus signs, the portions a, b, c, d are fed to the analogue unit to produce the quantities ac, bd, ad, be and the signs are fed to the digital unit. A truth table indicating the 16 combinations of the signs k 1 -k 4 enables Boolean equations to be drawn up for m, n, p, r. For instance m= k 1 k 3 +#k 1 #k 3 , p=k 1 k 4 +#k 1 k 4 and logic units can determine the values m, n, p, r. The equations assume that the real quantity in brackets is positive, e.g. if k 1 - k 4 = 1 then (a+jb (c+jd)= (ac - bd)+j(ad +bc) therefore m= + 1, n=-1. However, a correction of m must occur if ac<bd and the analogue-to-digital linkage allows these corrections to occur for m when n=-1, ac<bd, and for p when r=-1, ad<bc. A digitalto-analogue link is necessary to allow the signs n, r to be inserted in the mathematical operations. Division is performed using the equation: