i have Question about Inverse lapalce transform & plot
显示 更早的评论
hi. i try to cording matlab to draw a graph of inverse laplace transofrm result
F is a function made of R and G. and i want to inverse laplace transform that function F and draw a graph.
i really try hard but it didn't work. maybe there is a error at plot cording.
can i get a advice about it?
thank you.
here's my cording.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
syms s
R = 1/s
G = 75/(s)^2+10.25*s+100.65
F = R * G
a = ilaplace (F)
x = t
t = [0,0.01,10];
y = a;
plot(x,y)
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2 个评论
Paul
2021-5-11
Are you sure you don't mean:
G = 75/( s^2+10.25*s+100.65 )
jongil park
2021-5-11
采纳的回答
Try this —
syms s
R = 1/s
G = 75/(s)^2+10.25*s+100.65
F = R * G
a = ilaplace (F)
% x = t
t = [0 10];
y = a;
fplot(y,t)
grid
Use fplot, not plot, for symbollic plots.
.
5 个评论
Paul
2021-5-11
It's unfortunate that fplot() isn't smart enough to indicate the delta(t) at t = 0.
It does, actually.
It indicates a singularity at 0 (with a suitably high resolution). That’s likely the best it can do.
syms s
f = ilaplace(41*s/(4*s))
figure
fplot(f, [-1 1]*1E-500)
ylim([-1 1]*50)
.
jongil park
2021-5-11
Interesting. I tried a couple of other cases and that vertical dashed line only shows up when fplotting over a very small range as you did. I don't see why one should have to fplot over only microscopically small segments where one can't see the rest of the plot. I thought that vertical dashed line is used by fplot to indicate a singularity. I don't think delta(t) should be demarcated as a singularity, but I guess that may be arguable. However, other types of singularities show up on the plot without any special control of the x-limits
syms x real
fplot(1/x)
What I'd really like is for fplot() to show that delta(t) with an arrow, or something like that.
Star Strider
2021-5-11
@jongil park — As always, my pleasure!
@Paul — If you consider this to be a bug, or would like this as an ‘enhancement’, you can report it as such, request the enhancement, or both. Perhaps having this as an option (such as 'ShowDeltaFunction','on') would work.
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