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plotting - Help with debugging my code



In order to descrive the multifractal behaviour of a set, Baumann provides a code based on the functions Dq and Tau, given below.


       Dq[p_List, r_List] := 
       Block[{l1, l2, listrg = {}},(*----length of the lists---*)
       l1 = Length[p];

       l2 = Length[r];
       If[l1 == l2,(*----variation of q and determination of D_q---*)
       Do[gl1 = Sum[p[[j]]^q r[[j]]^((q - 1) Dfractal), {j, 1, l1}] - 1;
       result = FindRoot[gl1 == 0, {Dfractal, -3, 3}];
       result = -Dfractal /. result;
       (*----collect the results in a list---*)
       AppendTo[listrg, {q, result}], {q, -10, 10, .101}], Print[" "];
       Print[" Lengths of lists are different!"];
       listrg = {}];
       listrg]


       (*----calculate Tau---*)
       Tau[result_list] := 
       Block[{l1, listtau = {}},(*----lengths of the lists---*)
       l1 = Length[result];
       (*---calcultate Tau---*)
       Do[AppendTo[
       listtau, {result[[k, 1]], 
       result[[k, 2]] (1 - result[[k, 1]])}], {k, 1, l1}];
       listtau];



       p = {2/5, 2/5, 1/5};
       r = {1/3, 1/3, 1/3};
       ListDq = Dq[p, r];
       ListLinePlot[ListDq, AxesLabel -> {"q", "Dq"}]
       listTau = Tau[listDq];
       ListLinePlot[listTau, Joined -> {True, False}, 
       AxesLabel -> {"q", "\[Tau]"}, Prolog -> Thickness[0.001]]


The code above provides the plot of Dq but gives problems on Tau. In particular, the following errors are given:


enter image description here


Any ideas?



Answer



Two simple mistakes.


Tau[result_list] := should be Tau[result_List] :=


and


listTau = Tau[listDq]; should be listTau = Tau[ListDq];


Mathematica is case-sensitive. You must be careful about capitalization in identifiers.


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