FORTRAN

So I keep on having professor recommend that I should learn fortran at some point. I've got a pretty decent background in Visual Basic, C++, and Java, so could anyone give me a guess as to how hard it would be to teach myself? I'd mostly want it for plotting funky-ass functions and modelling systems. I've used Maple to this point, but it was a hassle and a half for my last assignment, so I'm curious to see if this might be an alternative I could persue.

Edit: And please don't tell me just to use another language. For some reason Fortran is still wildly popular in the scientific community, so I'd also like the ability to understand code from other sources without a whole lot of trouble.

How ya doing, buddy?