Find frequency from fourier transform

I have the following code which generates a sine wave of frequency 30Hz:

num_sam =1000; %number of samples
sam_int = 0.001; %sample interval in seconds
time = sam_int*(1:num_sam); %sample times, in sec's
sin_freq = 30; %in hertz
y = exp(1i*sin_freq*time);

I'd like to perform a Fourier transform of this wave to find the frequency, but every graph I get isn't peaking (if at all) at 30Hz. How can I achieve this?

Thanks.

[Adam]

Have you looked at

doc fft

? There are examples of how to do this.

Answer 1

[Honglei Chen]

The signal should be defined as

exp(1i*2*pi*sin_freq*time)

Otherwise, your frequency is scaled by 2*pi.

HTH