Iam triying to plot summatory of the next function:


I have no problem plotting a trigonometric fourier serie, so the only problem is plotting the complex i. I have watched several videos where they use an uppercase I instead of an lowercase i, I have already tried that but with no results. The functions that I use are:

s[i_,t_] := 1/2 + Sum[(e^(i*n*t*wo)*Sin[n*Pi/2])/(n*pi),{n,-i,-1}] + Sum[(e^(i*n*t*wo)*Sin[n*Pi/2])/(n*pi),{n,1,i}] 


First I made a declaration of a function where the summatories are declared, the i in the Plot[] function is the number of iterations.

I offer an apologize my english is not the best one and I dont know how to make the ecuation look pretty. Anyway thanks a lot.

  • 2
    $\begingroup$ You will want to use Re[] or Im[] to see the individual parts in Plot[], or use ReIm[] in conjunction with ParametricPlot[]. Also, the exponential constant is E (capitalization matters!) and the exponential function is Exp[]. $\endgroup$ – J. M.'s discontentment Mar 11 '16 at 17:41
  • 2
    $\begingroup$ First you should look at the Mathematica documentation for Exp, then also search for examples here. See this Q&A or this one, for instance. Your definition is incorrect because s uses two arguments but you in Plot you're calling it with just one. $\endgroup$ – Jens Mar 11 '16 at 17:46

This might be what you are after:

s[i_, t_] := 1/2 + Sum[(E^(I*n*t*wo)*Sin[n*Pi/2])/(n*Pi), {n, -i, -1}] + 
                   Sum[(E^(I*n*t*wo)*Sin[n*Pi/2])/(n*Pi), {n, 1, i}];
wo = 1; 
Plot[s[5, t], {t, -10, 10}]

enter image description here

| improve this answer | |
  • $\begingroup$ yeeei!!! Thanks, but could you please explain me why you use the I and the E? $\endgroup$ – Mac Mar 11 '16 at 17:59
  • $\begingroup$ Because as I said, capitalization matters, @Mac. Those are the symbols used by Mathematica for the constants you know. $\endgroup$ – J. M.'s discontentment Mar 11 '16 at 18:14
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    $\begingroup$ Consider the difference between ?E and ?e. $\endgroup$ – bill s Mar 11 '16 at 18:24

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