Set different Page-Per-Post for main page vs search results

I want to leave my Admin Option of Page-Per-Post set at 3, because I want my front page to show only three entries.
But I want the search results to show 10 post-per-page.

Would someone be able to tell me which PHP code file that contains the search code so that I can hard-code the search results to 10 while leaving the admin setting to 3.