I would like to create or generate white noise in the range of [-1 1], but I don't know exactly how to do it. My programming language of choice is matlab. As far as I know there exists a function named `randn` and also a function named `wgn` (white gaussian noise). So please help me with this issue, to clarify, for example I want to generate following equation:

```
x(t)=20*sin(2*pi*f1*t)+30*cos(2*pi*f2*t)+A3*white noise

```

where `A3=amplitude` and white noise is in the range [-1 1]. Please help me and clarify how to do it. My confusion is related to white noise, not about the others, let's assume that t is changing from 1 to 100.