How to define and plot a function with input range?

Question

0 个投票

Hi,

I have a function:

I need to plot it: y(t) = 2f(t-1) + 4f(t-2) + 3(ft-3) + f(t-4)

I could imagine what y(t) looks like but couldn't make the MATLAB code working after a lot of tries. I have:

pt = @(t) (1 ./ (1 + t .^ 2));

But I don't know how to specify the range of t (0.5 >= t >= -0.5).

I also tried piecewise():

pt = @(t) piecewise(0.5 >= t >= -0.5, (1 + t .^ 2) .^ (-1), t > 0.5, 0, t < 0.5, 0);
x = 0:0.01:10;
plot(x, pt(x));
xlim([-1 10]);

But it reported error: Undefined function 'piecewise' for input arguments of type 'double'.

Could you please help me with this? Thanks a lot!

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Answer 1

Alan Stevens 2021-10-24

0 个投票

Like so:

pt = @(t) (1 ./ (1 + t .^ 2)).*(t>=-0.5).*(t<=0.5);

x = 0:0.01:10;

y = 2*pt(x-1) + 4*pt(x-2) + 3*pt(x-3) + pt(x-4);

plot(x, y);

xlim([-1 10]);

Karl Bridggie 2021-10-24

pt = @(t) (1 ./ (1 + t .^ 2)).*(t>=-0.5).*(t<=0.5); does the trick!

Thanks very much!!