4
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I have next code

a = 1;
T = 25;
Subscript[I, 1] = If[t < T, a*t, 2*a*T - a*t];
Plot[Subscript[I, 1], {t, 0, 2 T}, AxesLabel -> {t, I1}]

enter image description here

I need to find average current on some interval, for this I do next

t1 = 1;
t2 = 5;
f = 1;
b = Table[If[i <= T, a*i, 2*a*T - a*t], {i, t1, t2, f}]
Subscript[I1, average] = Total[b]/Length[b]

It calculates average current correctly only to 25 value, after that all values are not correct. This error occurs because i don't include 25 value in false condition. How can I fix it? And How can I to get result in List form?

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2 Answers 2

Reset to default
5
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Plot[TriangleWave[x/100], {x, 0, 50}]

Integrate[TriangleWave[x/100], {x, 0, 50}]/50
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  • 3
    $\begingroup$ You need to divide by the base width of 50 to get there average of 1/2 $\endgroup$
    – Bob Hanlon
    Nov 29, 2016 at 1:54
2
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Using your code (in case you need to use Table):

a = 1;
T = 25;
i1[t_, T_, a_] = Piecewise[{{a*t, t < T}}, 2*a*T - a*t];
t1 = 1;
t2 = 5;
i1avg = {(Mean@Table[i1[t, T, a], {t, t1, Min[t2, T]}] Max[0, (Min[t2, T] - t1)] + 
          Mean@Table[i1[t, T, a], {t, Max[t1, T], t2}] Max[0, (t2 - Max[t1, T])])
         /(t2 - t1)
        }
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2
  • 1
    $\begingroup$ does this not give the same inaccurate result as the OP method? If you want to sum discrete values you should use the trapezoidal rule. $\endgroup$
    – george2079
    Nov 29, 2016 at 12:56
  • $\begingroup$ @george2079 Good catch! Didn't look at the underlying. Fixed the answer. $\endgroup$
    – Stitch
    Nov 29, 2016 at 14:27

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