I have produced used the following code to create a contour plot:
ContourPlot[Cos[x] + Cos[y], {x, 0, 4 Pi}, {y, 0, 4 Pi}]
However, I would like to modify this plot so that when the function is positive the shading is blue, and when it is negative the shading is red.
Now I know there's already similar threads on this site to achieving this but I would like to impose another condition which makes things trickier.
I would also like the contours lines to have the OPPOSITE colour to the shading (i.e if the region is shaded blue then I want the contours to be red). The contours can be isolated by turning shading off:
ContourPlot[Cos[x] + Cos[y], {x, 0, 4 Pi}, {y, 0, 4 Pi},
ContourShading -> None]
So I would like the contours to be coloured as follows:
Combined with the shading, I hope that the final image will look like this:
The Goal
I would be really grateful if someone could shed some light on this.
I'm really hoping there's a way of implimenting an IF statement which will condition on the sign of the function.
Thanks in advance!