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Dynamics cheat sheet

my dynamics notes - 12000.org

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Where<br />

F n = 2 T<br />

F 0 = 2 T<br />

∫ T<br />

0<br />

∫ T<br />

0<br />

2π<br />

−in<br />

f (t) e T t dt<br />

f (t) dt<br />

Another way to write the above is to use the classical representation using cos and sin. The same coefficients<br />

(i.e. the same series) will result.<br />

˜f (t) = a 0 +<br />

a 0 = 1 T<br />

n=1<br />

∫ T<br />

0<br />

a n = 1<br />

T/2<br />

b n = 1<br />

T/2<br />

N∑<br />

a n cos n 2π N T t + ∑<br />

b n sin n 2π<br />

T t<br />

f (t) dt<br />

∫ T<br />

0<br />

∫ T<br />

0<br />

n=1<br />

(<br />

f (t) cos n 2π )<br />

T t dt<br />

(<br />

f (t) sin n 2π )<br />

T t dt<br />

Just watch out in the above, that we divide by the full period when finding a 0 and divide by half the period<br />

for all the other coefficients. In the end, when we find ˜f (t) we can convert that to complex form. The complex<br />

form seems easier to use.<br />

15

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