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I am trying to plot the values of the functions f[x] and der[x], but I am getting an empty plot. I am new to both Mathematica and simulation. Can anyone please help me. 

Manipulate[
  fu[alfa], 
  {{alfa, 1, "α"}, 0, 1, 0.001, Appearance ->"Labeled"},
  Initialization :> (
    fu[alfa_] := 
      Module[{α, f, der},
        α = alfa;
        f[x_] = Exp[x];
        der[x_] = Sum[((t)^(k) x^(-α))/Gamma[k + 1 - α], {k, 0, ∞}];  
        Plot[{f[x],der[x]}, {x, 1, 1.5},
          AxesLabel -> 
            {Style["x", Italic],
             Row[{Style["f", Italic], "(", Style["x", Italic], ")"}]}, 
          ImageSize -> {300, 200}, 
          ImagePadding -> {{35, 20}, {20, 20}}, 
          PlotStyle -> Thick]])]
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  • 1
    $\begingroup$ This code cannot be copied into a notebook in its current state because of syntax errors. For example, [Alpha] is not a valid symbol name. $\endgroup$
    – Sjoerd Smit
    Jun 24 '19 at 8:20
  • $\begingroup$ what is the value of t in Sum[((t)^{k)...]? $\endgroup$
    – kglr
    Jun 24 '19 at 8:36
  • 2
    $\begingroup$ When ever you can't get a complicated piece of code to work, a good strategy is to start first with something that does work, a simple plot, then add one component to it, get it working, then add another and slowly build it back up until you add a piece that causes it to fail then focus your attention on getting that single piece to work. $\endgroup$
    – Dominic
    Jun 24 '19 at 10:25
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There are quite a few programming errors in your code. Probably the most deadly one is not taking into account that der depends on three parameters, x, alfa and t.

Here is a rewrite of your code that produced a plot that can be manipulated. Note, because the evaluation of der is time consuming, response to moving the sliders is rather sluggish.

Clear[f, der]
f[x_] := Exp[x]
der[x_, α_, t_] :=  Sum[t^(k) x^(-α)/Gamma[k + 1 - α], {k, 0, ∞}]

Manipulate[
  Plot[{f[x], der[x, alfa, t]}, {x, 1, 1.5},
    PlotRange -> {0, 5},
    PlotStyle -> Thick,
    AxesLabel ->
      {Style["x", Italic], 
       Row[{Style["f", Italic], "(", Style["x", Italic], ")"}]}, 
    ImageSize -> {300, 200},
    ImagePadding -> {{35, 20}, {20, 20}}],
  {{alfa, 1, "α"}, 0, 1, 0.01, Appearance -> "Labeled"},
  {{t, .2}, 0, 1, 0.01, Appearance -> "Labeled"}]

demo

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1
  • $\begingroup$ Thank you for your comments $\endgroup$
    – vicky
    Jun 26 '19 at 7:22

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