<p>I'm trying to write an audio analysis application, and I need to identify local maxima in a 2D array which represents a spectrogram. I've already got an open source library that can generate the spectrogram using Fast Fourier Transforms, but I was wondering if anybody knew of any good libraries to help me with actually finding the maxima? I'm not quite sure what to search Google for - the best I could think of was "numerical library" but that hasn't got me very far.</p>

<p>Preferably in C, but I'm open to other suggestions.</p>

No, I don't believe so.
Certainly the C# compiler disallows it when converting a lambda expression:
```
```
int x;
Expression<Func<int,int>> foo = (x=y); // Assign to x and return value
```
```
This yields the error:
```
```
CS0832: An expression tree may not contain an assignment operator
```
```