The speaker tries to describe love using the language of mathematics, as if feeling alone isn't big enough. Each stanza imagines something that must exist somewhere in the abstract world of numbers: a number that secretly contains a portrait of the beloved, a function that captures the beauty of her body, an algorithm that can copy the speaker's love. These things are unfindable, buried past the millionth decimal or "yet to be discovered," which suggests that the beloved is almost too perfect to be measured or captured.
The tone shifts at the end. The "lemming cells" rushing toward self-destruction make the love feel overwhelming and slightly dangerous, something that undoes the speaker rather than comforts him. The mood is playful and nerdy at first, then turns more intense and vulnerable. The cool, logical vocabulary ends up showing how uncontrollable the emotion really is.