<p>EPFL offers a three-year one subject degree. If OP is genuinely interested in applied math as opposed to pure math then he should go to EPFL. For people in the know, EPFL doesn’t have as good a reputation as ETHZ, at least in physics. Outside of academics, people in the US know absolutely nothing about either. The only drawback to EPFL is that it’s a train ride away from Lausanne centre ville and student housing. My impression of Swiss universities was favorable from having studied French language and civilization in nearby Neuchâtel. However, I knew someone who transferred from EPFL in physics to an American LAC because his physicist father moved back to the US from CERN.</p>
<p>I assume OP will receive no credit from EPFL for study at Grinnell and be starting as a first year student. I would contact Grinnell and say that you want to take a year off and study abroad. If OP likes EPFL, he can choose to stay and if not just go back to Grinnell and apply to get math/CS credit for a year away.</p>
<p>Grinnell, Iowa or Lausanne, Switzerland? Some choice! </p>