do a blog Search using Valentine
Two of the poems in the anthology that Sarah Glaz and I edited -- Strange Attractors: Poems of Love and Mathematics (AK Peters/CRC Press, 2008) -- have the title "Valentine." Here is the final line of the one by Katharine O'Brien:
. . . won't you be my cardioid?
and the final pair of lines of Michael Stueben's verse:
I love you as one over x,
as x approaches zero.
Sending my wishes a week ahead of time, Happy Valentine's Day!