False position method and regula falsi method are two early, and still current, names for a very old method for solving an equation in one unknown. == Brief background == To solve an equation means to write, or determine the numerical value of, one of its quantities in terms of the other quantities mentioned in the equation. Many equations, including most of the more complicated ones, can be solved only by iterative numerical approximation. That consists of trial and error, in which various values of the unknown quantity, referred to here as “x”, are tried. That trial-and-error may be informed...