[Maxima] span(M)

[Chris Sangwin]

Dear Maxima,

I notice that the command nullspace(M); returns a Maxima object "span".

Is there a predicate function which determines if another vector belongs 
to this span?

e.g. inspanp(M,v).

I've looked in the manual,
http://maxima.sourceforge.net/docs/manual/en/maxima.pdf
but can't find the answer there.

Thanks
Chris