Like other commenters have said, it depends a lot on what programs you're writing. You might want to know some harmonic analysis if you're writing audio softwa

Like other commenters have said, it depends a lot on what programs you're writing. You might want to know some harmonic analysis if you're writing audio software. On the other hand, if you're making user interfaces, knowing a little bit of geometric math (vector algebra, trigonometry, calculus) can go a long way.