So I'm writing a composition with a ground bass, and I'm wondering whether there are any examples of classical music, where the ground bass varies in tune. I've seen several example of them that change in key with the music, but I was just wondering whether it can vary in any other way.
According to classical theory, Ostinato, or ground, bass, cannot produce variations within its part during the music. The part is persistent, constantly repeating, while variations on the parts of other instruments play over the ostinato bass.
This isn't to say that an ostinato bass part cannot be interesting (obviously) or that the part itself cannot change during the course of the song - a key-change may bring about a new ostinato bass part that will then persistently repeat until the next key-change (usually returning to the initial ostinato part.)
It's jazz but, please consider this piece by Jaco Pastorius:
If it varies, it is by definition no longer a ground bass. Having got that over, SHOULD you allow yourself to compose a piece with a not-quite-ground bass? A slight variation to accommodate a final cadence or coda section wouldn't be a weakness in my opinion. Random variation might. What do you think?