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This question already has an answer here:

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? img

Thank you in advance.

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marked as duplicate by Jason B. plotting Aug 23 '18 at 20:42

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

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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
 ]

enter image description here

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
 ]
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  • $\begingroup$ Thank you very much! $\endgroup$ – MarV Aug 24 '18 at 11:43
  • $\begingroup$ You're welcome! $\endgroup$ – Henrik Schumacher Aug 24 '18 at 12:18

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