Can someone who has access to Mathematica, please, help me in drawing this RegionPlot with high precision. (I used the basic plan of WolframCloud which I could not increase the precision). I do not want to use the result, I just want to know their shape, so, only a less quality image of the results can help me.

I want to know the following RegionPlot for different values of $$a=\{0,\frac12,\frac13,\frac5 {13},8.13, 20.353\}$$

a:=0;

RegionPlot[      (2 Sin[b x] Sin[b x-2 π x] Sin[a π-π x] Sin[a π+π x])>0     ,   {x,1000,1010}  ,{b,0,π}    ,  PlotPoints->100    ]

$$$$


Here we also use ContourPlot and set Contours->{0},ContourShading->{None,Blue} instead of RegionPlot.

• a=0
fig1 = With[{a = 0},
ContourPlot[
2 Sin[b x] Sin[b x - 2 π x] Sin[a π - π x] Sin[
a π + π x], {x, 100, 110}, {b, 0, π},
Contours -> {0}, ContourShading -> {None, Blue},
ContourStyle -> None, BoundaryStyle -> Automatic, PlotPoints -> 50,
MaxRecursion -> 2]]


• a=5/13

• Thank you very much. Sorry, I miswrote the domain, I meant $\{x,1000,1010\}$ which will be simpler. Could you please use RegionPlot instead? Jul 29, 2021 at 13:56
• thanks again @cvgmt. Jul 29, 2021 at 14:01
• As my final request, may I ask you to please provide these two results for $\{{x,100,110}\}$ as well? Since it seems that for large values of $x$, the plots are not clear. @cvgmt Jul 29, 2021 at 14:05
• Thank you very much for your time and for your favor. @cvgmt Jul 29, 2021 at 14:12
• @charmin I think ContourPlot is better than RegionPlot` for high precision. Jul 29, 2021 at 14:12