New guy and programming problem

[Thomas Klemm]

Fun fact: These trigonometric identities were used for multiplication and division before logarithms were known.

Cf. Prosthaphaeresis

Quote:Notice how similar the above algorithm is to the process for multiplying using logarithms, which follows these steps: scale down, take logarithms, add, take inverse logarithm, scale up. It's no surprise that the originators of logarithms had used prosthaphaeresis. Indeed the two are closely related mathematically. In modern terms, prosthaphaeresis can be viewed as relying on the logarithm of complex numbers, in particular on Euler's formula:

\(e^{ix}=\cos x+i\sin x\)

I find it interesting that this technique was developed using complex numbers under the hood while they weren't discovered yet.

Cheers
Thomas