I want to make a simple contour plot with a function that takes positive and negative values (see below). I need the absolute values of the function to take the same shade in the contour plot (and greyscale would be best). Ultimately, I want the figure to look like a curved hill, where the top of the hill is the 0 contour.
Also, it would be great if I could remove the defined contour lines and smooth out the borders of the contours.
Thanks if you can help!
ContourPlot[(1 - c N z)/(N z - c N z^2) /. {c -> .01}, {N, 2, 50}, {z,