No, there does not appear to be any public domain MATLAB software for that purpose. I think I found some open source that might work; I also found some software that appeared to be free to purchasers of a particular book. I found routines that were part of thesis work -- but thesis work is automatically copyrighted.
In order for source code to be public domain, it is required that the code include wording that clearly places it in the public domain, which is something that has specific legal meaning, and allows anything to be done with the source except claiming to be the copyright owner of it. This is different from any of the open source licenses; open source licenses reserve some rights. Free Software Foundation has successfully litigated to prove that one of the GNU licenses is not "public domain" -- thereby allowing FSF to preserve the right to prohibit various forms of commercial use. For example the licenses that require that anyone who obtains a binary executable of the program must be provided source code upon request, are not public domain: reserving any rights "cancels out" public domain status in law.
If you are looking for source code that can be used in a for-profit package without payment, you might be able to find that -- but the code probably will not be public domain.
