# Epilog: Only one point appears in graph [duplicate]

I'm trying to graph something for a paper and I want to highlight two points in two function. I am using this code:

    Show[
Plot[f[x, 50, .5, 1, .8, 3], {x, -3, 3}, PlotRange -> All,
Epilog -> {Red, PointSize[Large],
Point[{x[0, 50, .5, 1, .8, 3],
f[x[0, 50, .5, 1, .8, 3], 50, .5, 1, .8, 3]}]}],
Plot[f[x, 50, .5, .7, .8, 3], {x, -3, 3}, PlotRange -> All,
Epilog -> {Green, PointSize[Large],
Point[{x[0, 50, .5, .7, .8, 3],
f[x[0, 50, .5, .7, .8, 3], 50, .5, .7, .8, 3]}]}]]


Where

x[cost_, t_, teta_, qa_, qv_, b_] :=
2 Log[((3/2)*cost +
Sqrt[(cost^2)*(9/4) + 4 (((t - b) t)^1.5) (1 + teta) qa*qv])] -
2 Log[2 (1 + teta) qa (t - b)^1.5]

f[x_, t_, teta_, qa_, qv_,
b_] := ((t - b)^1.5)*
qa*(1 + teta) E^(-1/8) (1 - Erf[(2 x - 1)/Sqrt[8]]) + (t^1.5)*qv*
E^(-1/8)*(1 + Erf[(2 x + 1)/Sqrt[8]])


My output however only shows one of the points...Am I doing anything wrong or is it just the programme?

• Aug 23, 2018 at 17:03

The value of Epilog option for Show is taken from the first plot, so the one from the second plot is ignored. As alternative, simply specify the Epilog directly in Show.

epi1 = {Red, PointSize[Large],
Point[{x[0, 50, .5, 1, .8, 3],
f[x[0, 50, .5, 1, .8, 3], 50, .5, 1, .8, 3]}]};
epi2 = {Green, PointSize[Large],
Point[{x[0, 50, .5, .7, .8, 3],
f[x[0, 50, .5, .7, .8, 3], 50, .5, .7, .8, 3]}]};
Show[
Plot[f[x, 50, .5, .7, .8, 3], {x, -3, 3}],
Plot[f[x, 50, .5, 1, .8, 3], {x, -3, 3}],
Epilog -> {epi1, epi2},
PlotRange -> All
]


Btw., this has the same effect and is somewhat more transparent to me:

Show[
Plot[f[x, 50, .5, .7, .8, 3], {x, -3, 3}],
Plot[f[x, 50, .5, 1, .8, 3], {x, -3, 3}],
Graphics[{epi1, epi2}],
PlotRange -> All
]

• Thank you very much!
– MarV
Aug 24, 2018 at 11:43
• You're welcome! Aug 24, 2018 at 12:18