Uh oh! Wolfram|Alpha doesn't run without JavaScript.
Please enable JavaScript. If you don't know how, you can find instructions
here
.
Once you've done that, refresh this page to start using Wolfram|Alpha.
plot from -pi to pi abs((1+exp(-i*2w)+exp(-i*w)+exp(-i*6w)+exp(-i*7w))
Natural Language
Math Input
Extended Keyboard
Examples
Upload
Random