I have written a fast, memory efficient implementation of the Weighted Histogram Analysis Method (WHAM). I've compiled and tested on a number of platforms and it's vanilla ANSI C, so the odds are good it'll work almost anywhere (or at least anywhere sufficiently unix-like). It is released under the GPL and BSD licenses, so you can take your pick of whichever you're more comfortable with. However, if you're using the code, I'd appreciate it if you'd let me know.
Download current version
The current version of the source is available here.
All versions can be found here.
The WHAM manual is available online in html and pdf forms. For a discussion of the theory and practice of using WHAM to compute PMFs, you can download the slides from a talk I gave. If you have questions, suggestions, patches, or complaints, I can be reached at email@example.com.
If you use this code in the course of published research, please reference it as:
Grossfield, Alan, "WHAM: the weighted histogram analysis method", version XXXX, http://membrane.urmc.rochester.edu/content/wham