I am currently a first-year Ph.D. student in computer science in Europe. I have published some papers in the top-venue conferences.
Recently, we are looking into a new field that requires strong mathematical background, but unfortunately, my math skills are not that steady. Whenever I encounter something I don't understand, I am always confused about whether I should have learned it in the basic courses and don't know how to catch up with it. I am also worried that my supervisor would think me less qualified if I admit that I am not sure about something.
I am wondering how people manage this. Should I just be strait-forward with my supervisor? What would he think of me and what would he probably do?
--- Edit ---
Thanks for all of your replies and suggestions. I especially appreciate the answers/comments from the perspective of supervisors since I really have no idea how my supervisor would react to it. I am probably overthinking and feeling less confident in this new field. It is also good to know that I am not the only one who faces this problem.
After all, I think I would first try to find some references and teach myself first though it may be very challenging to me since I am sure what courses/subjects would cover the specific techniques I need for my research. If it still doesn't work out, I would show what I have tried during the past week and see if my supervisor could point me to any further resources.