# Wave equation

1. Jan 3, 2006

### darkar

From equation (8) to equation (9) fro the link attached below which the equation is written into a complex form. But why can it be written in that form even though the equation do not have an imaginary part isin(omega*t-kz+phi)?

http://scienceworld.wolfram.com/physics/WaveEquation.html

2. Jan 4, 2006

### dicerandom

Good question

It's a matter of convention, we usually just ignore the imaginary part (note that this is not always the case though, for instance in Quantum Mechanics we often need the imaginary part as well). The reason waves are usually expressed as complex exponentials is that it makes the math easier (believe it or not), it's a lot easier to perform various additions, multiplications, etc. with an exponential than it is to try and slough through trig identities.