Ah. Got it. (I saw the word minimum in the title, but not in the message.)
I think it's pretty much as simple as just subtracting the desired minimum from the input. If, in doing so, you want to keep the domain maximum the same (rather than just offsetting the whole domain by a certain amount) then you'll also have to resize the domain to be (maximum-minimum). Here's an example.
Hey, sorry to resurrect, but I have the same question, almost. The fix mentioned by Christopher Dobrian will not solve the issue when you want to use [function] in a bang-able manner, i.e., when you want to send a message output to a [line~] or [curve~].
Is there any way to affect [function] so it sends out a list with a non-zero x minimum?