Classic running out of memory... huh? what? <not so long>

[Bruce Labitt]

How can one check to see how much memory is required for a library?  I 
compiled FFTW for use in my code.  For an FFT of length N, how can one 
find out how much overhead there is?  Is there a way externally (sans 
code crawl)?

I have communicated with the author(s) previously - isn't that the 
greatest about Open Source - so querying them is not out of the 
question.  In general is there a way to experimentally do this?  What 
tools are needed?  (valgrind again?)

-Bruce