A contour plot is a nice way to represent 2D data. Mathematica has some great tools for constructing such plots, but you might want to tweak the fonts and graphics a bit. Sometimes fonts should be enlarged so that they are visible e.g. in a journal article where there is not too much space to use.

The following code returns a contour plot of the Riemann zeta function's absolute value in an area in the complex plane; Text fonts are enlarged from default. Only values under are plotted. Values above that are “clipped” away as white colour. By definition of the absolute value, values are always more than 0, otherwise values under 0 would get clipped away with black colour. Contours are drawn in intervals of , as adjusted in the Range function.

max = 2; ContourPlot[Abs[N[Zeta[x + y*I]]], {x, -2, 10}, {y, -10, 10}, PlotLegends -> BarLegend[{"Rainbow", {0, max}}], ColorFunction -> "Rainbow", ContourStyle -> Black, Contours -> Function[{min, max}, Range[min, max, 0.1]], PlotLabel -> Style["Absolute value of the Riemann zeta function", 16, Bold], BaseStyle -> {FontSize -> 15}, FrameLabel -> {Style["Real axis" , 16, Bold], Style["Imaginary axis", 16, Bold]}, PlotRange -> {0, max}, ClippingStyle -> {Black, White}]

References:

- reference.wolfram.com
- Díaz-Francés, Eloísa; Rubio, Francisco J. (2012-01-24). "On the existence of a normal approximation to the distribution of the ratio of two independent normal random variables". Statistical Papers. Springer Science and Business Media LLC.