[math-fun] Elliptic curve calculator

You may be aware of the Abelian group operation on elliptic curves. We can exploit this to multiply, divide and square-root real numbers just by drawing a straight line on an elliptic curve marked with two logarithmic scales: http://cp4space.wordpress.com/2012/08/29/elliptic-curve-calculator/ I've tried it on a printed version, and can achieve somewhere between 2 and 3 significant figures of precision, depending on the calculation. Obviously it is of no practical use today, since we have electronic calculators and so forth. But in theory, this could have been made way back in 1830, when it could have been used for calculations in navigation and ballistics. Sincerely, Adam P. Goucher http://cp4space.wordpress.com/