Problem with eval and symbolic inequation

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Anna Silva Ferreira
回答： Mischa Kim 2016-9-16
I am trying to calcendulate the equation below in the manner and I can not.
syms t
syms joelho(t)
joelho(t) = ((0.15*sin(5*pi*t - pi/2) + 0.15)*heaviside(t)*(t<0.4) + (0.53625*sin(10*pi*t/3 + pi/6) + 0.53625)*heaviside(t - 0.4))*180/pi;
t = 0;
s = eval(t);
The following error appears:
Undefined function 'eval' for input arguments of type 'double'.
Error in teste4 (line 8)
s = eval(t);
the result is zero.
  1 个评论
Mischa Kim
Mischa Kim 2016-9-16
编辑：Mischa Kim 2016-9-16
What exactly are you trying to do? Evaluate joelho(t) at t = 0 ?

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回答（1 个）

Mischa Kim
Mischa Kim 2016-9-16
Anna, try
syms t
joelho = ((0.15*sin(5*pi*t - pi/2) + 0.15)*heaviside(-t - 0.4) + ...
(0.53625*sin(10*pi*t/3 + pi/6) + 0.53625)*heaviside(+t - 0.4))*180/pi;
s = subs(joelho,t,0) % evaluate expression at t = 0
ezplot(joelho,[-2,2]) % plot

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