PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

(sharon) #1

Fourier and Laplace 343


F1 =
pi*Dirac(w-3)+pi*Dirac(w+3)

>> F2 = fourier(cos(3*t+pi/4)) % part (b)

F2 =
1/2*2^(1/2)*pi*Dirac(w-3)+1/2*i*2^(1/2)*pi*Dirac(w-
3)+1/2*2^(1/2)*pi*Dirac(w+3)1/2*i*2^(1/2)*pi*Dirac(w+3)

>> factor(F2)

ans =
1/2*2^(1/2)*pi*(Dirac(w-3)+i*Dirac(w-3)+Dirac(w+3)- i*Dirac(w+3))

>> F3 = fourier(sin(3*t)) % part (c)

F3 =
-i*pi*Dirac(w-3)+i*pi*Dirac(w+3)

>> F4 = fourier(1/t) % part (d)

F4 =
i*pi*(Heaviside(-w)-Heaviside(w))

>> F5 = fourier(exp(-t)*sym(‘Heaviside(t)’),t,w) % part (e)

F5 =
1/(1+i*w)

>> pretty(F5)

1
-------
1 + i w

>> F6 = fourier(t*exp(-t)*sym(‘Heaviside(t)’),t,w) % part (f)

F6 =
1/(1+i*w)^2

>> F7 = fourier(exp(-abs(t)),t,w) % part (g)

F7 =
2/(1+w^2)

>> F8 = fourier(sym(‘Heaviside(t+1)’)
-sym(‘Heaviside(t- 1)’),t,w) % part (h)
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