Dear all(adsbygoogle = window.adsbygoogle || []).push({});

I am looking to write my own computer program for a Fourier transform. However my maths is very rusty and I will need to recap some things.

I am struggling a little bit to recall the rules for the period of sines (or cosines) when they are MULTIPLIED. I haven't had much luck Googling this.

Am I right in thinking that for two waves ADDED their common period is their two periods multiplied (the lowest common multiple) ?

e.g.

y=cos(2.pi.2x) + cos(2.pi.3x) Fundamental period = 1/2 x 1/3 = 1/6?

But what if the two sines (or cosines) are multiplied?

e.g.

y=cos(2.pi.2x).cos(2.pi.3x)

Can anybody explain the rules for the addition and multiplication cases, without going into heavy maths?

Thank you

Matt

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Period of added/multiplied sines/cosines

**Physics Forums | Science Articles, Homework Help, Discussion**