RegionPlot[{x<1 && y<1 &&x+2(x y)^(1/2)<1,
y<1&&x>1&&1/x+2(y/x)^(1/2)<1,
((1/(x y))^(1/2) +(x/( y))^(1/2))^(2)<4 ,
x y<1/4&&y>1&&x+2(x y)^(1/2)<1,
y/ x<1/4&&y>1&&1/x+2(y/x)^(1/2)<1}, {x, 0,9}, {y,
0, 3}, LabelStyle ->{15,Bold,Black},PlotPoints->100,
Axes -> True, Frame -> True,FrameLabel->{ "|\!$$\*SubscriptBox[\(u$$, $$1$$]\) / \!$$\*SubscriptBox[\(u$$, $$3$$]\)|","|\!$$\*SubscriptBox[\(u$$, $$2$$]\)|"
},RotateLabel -> False, FrameStyle -> Directive[Black, 10],
PlotStyle -> {Red, Green, Cyan, Yellow, Orange}]


I have the above code to plot a few regions. Now I want to label each regions as done in a similar image shown below. I want to add R_1 , R_2 .. exactly as shown in the picture. How can I do it in Mathematica itself?

funcs = {x < 1 && y < 1 && x + 2 (x y)^(1/2) < 1,
y < 1 && x > 1 && 1/x + 2 (y/x)^(1/2) < 1,
((1/(x y))^(1/2) + (x/( y))^(1/2))^(2) < 4 ,
x y < 1/4 && y > 1 && x + 2 (x y)^(1/2) < 1,
y/ x < 1/4 && y > 1 && 1/x + 2 (y/x)^(1/2) < 1};

framelabels = TraditionalForm /@ {Abs[Row[{Subscript[u, 1], "/", Subscript[u, 3]}]],
Abs[Subscript[u, 2]]}


You can use the option PlotLabels:

RegionPlot[funcs, {x, 0, 9}, {y, 0, 3},
PlotLabels -> Join[Placed[#,Center] & /@ labels[[;;3]],
{Placed[labels[[4]], {{.2, 1.15}, {.5, .5}}], Placed[labels[[5]], Center]}],
LabelStyle -> {15, Bold, Black}, PlotPoints -> 100,
Axes -> True, Frame -> True, FrameLabel -> framelabels,
RotateLabel -> False, FrameStyle -> Directive[Black, 10],
PlotStyle -> {Red, Green, Cyan, Yellow, Orange}] /. Opacity[2/3]->Opacity[0]


• Thanks. You just nailed it. Except for the R_4. It is not transparent so a part of the region is not visible Apr 22, 2020 at 18:56

You could try Epilog

RegionPlot[{x < 1 && y < 1 && x + 2 (x y)^(1/2) < 1,
y < 1 && x > 1 && 1/x + 2 (y/x)^(1/2) < 1,
((1/(x y))^(1/2) + (x/(y))^(1/2))^(2) < 4,
x y < 1/4 && y > 1 && x + 2 (x y)^(1/2) < 1,
y/x < 1/4 && y > 1 && 1/x
+ 2 (y/x)^(1/2) < 1}, {x, 0, 9}, {y, 0, 3},
LabelStyle -> {15, Bold, Black},
PlotPoints -> 100, Axes -> True, Frame -> True,
RotateLabel -> False, FrameStyle -> Directive[Black, 10],
PlotStyle -> {Red, Green, Cyan, Yellow, Orange},
ImageSize -> 400,
Epilog -> {
{Style[Text["R3", {2.8, 2.2}], 14]},
{Style[Text["R5", {8, 1.2}], 14]},
{Style[Text["R1", {.2, .2}], 10]},
{Style[Text["R4", {.2, 1.2}], 10]},
{Style[Text["R2", {6, 0.5}], 14]}
}
]


You can play with Style and Text to change these.

• Thanks. But is it possible to get the particular font of 'R' with subscript exactly as in picture I uploaded? Apr 22, 2020 at 16:30