Sorry if this is a little off-topic.  I'm trying (and failing) to use 
Matlab to match the waveforms produced by the viewSamples method from 
the FMSound class.  My equation is:

y = sin(2*pi*fc*t + m*sin(2*pi*fm*t))

I'm using the values from the modulation:ratio: method such that in the 
equation above 'm' is the modulation: argument and 'fm' is computed 
from 'fc' divided by the ratio: argument.

The only case that looks even remotely correct is for modulation: 1.0 
ratio: 1.0.

The mixSampleCount:into:startingAt:leftVol:rightVol: method seems to be 
doing the synthesis work, but for whatever reason this method seems 
kind of hard to follow.

Can someone familiar with FMSound help me understand what's going on in 
that class in terms of my equation?

Thanks.

-Dave