Mathematica for Physics -- problems Hi I'm trying to work out the solved examples in the book "Mathematica for Physics" [The code is available at http://library.wolfram.com/infocenter/Books/4539/]. But I am unable to plot anything despite using the plot commands given in the book. Specifically, looking at ch9.nb (available from this link) -- problem 4 (particle propagating toward a rectangular potential), the commands given produce blank plots. I am able to plot simple functions, so I think the problem is with these commands. I've attached my code with this thread. I'd be really grateful if someone could help me out with this. Thanks.