If I'm understanding this correctly, before programmable computers were invented, the only way to do complex calculations was to use a slide rule.
But hold on — to construct a slide rule, you need to somehow compute the logarithms of all the numbers on the rule. But calculating logarithms is hard. Like, really hard!
So how on Earth did people make slide rules having logarithmic markings on them?
(Indeed, some slide rules have a bunch of additional scales for trigonometry and so on. Same question: how do you calculate where to put the tick marks?)