# How to control the axis interval in ContourPlot [closed]

I have the following equation

p = 1.6; α = 0.001; r = 0.6; η = 0.04; ω = 1;
R ω p Sin[ω τ] + R ω p α - 9/4 r p R^3 ω - η p R == 0


If I use the following command

ContourPlot[R ω p Sin[ω τ] + R ω p α - 9/4 r p R^3 ω - η p R == 0,
{τ, 0, 20}, {R, 0, 2}, ContourStyle -> {Directive[Blue, Thick]}]


I am getting a plot where the x axis values are displayed at an interval of 5, i.e 0,5,10...., Is it possible to control the x axis interval ,like 0,2,4. Please suggest.

## closed as off-topic by Bob Hanlon, José Antonio Díaz Navas, MarcoB, J. M. will be back soon♦Mar 29 '18 at 1:19

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• Probably, you are looking for the options Ticks or FrameTicks... – Henrik Schumacher Mar 25 '18 at 13:54

You could use the internal functions ChartingScaledTicks and ChartingScaledFrameTicks to control how many tick marks are displayed. For example:

ContourPlot[
R ω p Sin[ω τ]+R ω p α-9/4 r p R^3 ω-η p R == 0,
{τ, 0, 20},
{R, 0, 2},
ContourStyle->{Directive[Blue,Thick]},
FrameTicks->{
{Automatic,Automatic},
{
ChartingScaledTicks[{Identity,Identity}][0,20,{10,2}],
ChartingScaledFrameTicks[{Identity,Identity}][0,20,{10,2}]
}
}
] The third argument, {10, 2} specifies that approximately 10 major divisions and 2 minor divisions per major division should be used.

• Thank you very much. – Udichi Mar 26 '18 at 10:23

Actually, ContourPlot is a framed plot that by default doesn't show axes ticks. What you need to do is define a set of custom frame ticks. Like so.

tickF[f_Function, min_, max_] := f /@ Range[Floor @ min, Floor @ max]
btmTicks[min_, max_] := tickF[{#, If[Mod[Round @ #, 2] == 0, #, ""]} &, min, max]
topTicks[min_, max_] := tickF[{#, "" } &, min, max]

p = 1.6; α = 0.001; r = 0.6; η = 0.04; ω = 1;
ContourPlot[
R ω p Sin[ω τ] + R ω p α - 9/4 r p R^3 ω - η p R, {τ, 0, 20}, {R, 0, 2},
Contours -> {0}, Note: I have changed the 1st argument given to ContourPlot from the form expression == 0 to the form expression and added additional contour options because my version of Mathematica (V11.1.1) has a bug that produces a horrible looking and incorrect tooltip value for the contours. These changes are a work-around that produces the correct tooltip. Your version of Mathematica may not have this paticular bug and, if so, you can ignore those changes.