How do I correctly plot this function?

Hello, I'm trying to generate a plot with the x I found, which was 92, that shows a curve that is just below the limit, which is 50. I can't seem to get a smooth plot/curve. I think it's because I might be plotting the wrong data. Any ideas on what I'm doing wrong? The rest of the code should be correct, it's just the plotting towards the end. Thank you!

function y = glucose_response_f(tt,K,tau,x)
syms t s
u = 5*((heaviside(t)-heaviside(t-5))+(heaviside(t-x)-heaviside(t-(x+5))));
U = laplace(u);
T = K/(s+1/tau)^2;
yt = ilaplace(T*U);
pretty(yt);
y = subs(yt,{t},tt);
disp('')
disp(['y=' num2str(double(y)) '[%]'])
end

%Command window
tt = [0 25 50 75 100 125 150 175 200];
K=0.1;
tau=40;
x=92;
y = glucose_response_f(tt,K,tau,x);

%Ans

heaviside(t - 5) (1600 #3 + 40 #3 (t - 5) - 1600) / t \ / t \

------------------------------------------------- - t exp| - -- | 20 - exp| - -- | 800

2 \ 40 / \ 40 /

heaviside(t - 92) (1600 #2 + 40 #2 (t - 92) - 1600)

- ---------------------------------------------------

2

heaviside(t - 97) (1600 #1 + 40 #1 (t - 97) - 1600)

+ --------------------------------------------------- + 800

2

where

/ 97 t \

#1 == exp| -- - -- |

\ 40 40 /

/ 23 t \

#2 == exp| -- - -- |

\ 10 40 /

/ 1 t \

#3 == exp| - - -- |

\ 8 40 /

y=0 31.9969 36.2006 29.5863 33.179 49.8597 43.87 32.6788 22.4144[%]

plot(tt,y)

[Walter Roberson]

Are you talking about this? If so then you are limited by the small number of tt values.

%Command window
tt = [0 25 50 75 100 125 150 175 200];
K=0.1;
tau=40;
x=92;
y = glucose_response_f(tt,K,tau,x);

y=0      31.9969      36.2006      29.5863       33.179      49.8597        43.87      32.6788      22.4144[%]

plot(tt, y)

function y = glucose_response_f(tt,K,tau,x)
    syms t s
    u = 5*((heaviside(t)-heaviside(t-5))+(heaviside(t-x)-heaviside(t-(x+5))));
    U = laplace(u);
    T = K/(s+1/tau)^2;
    yt = ilaplace(T*U);
    % pretty(yt);
    y = subs(yt,{t},tt);
    disp('')
    disp(['y=' num2str(double(y)) '[%]'])
end

[Ethan Hoang]

Yes that is what I got. I'm not sure if that graph is correct since it's not a smooth curve. Do you have any suggestions in plotting it differently?

[Walter Roberson]

Add more values to the tt list.

[Ethan Hoang]

I tried what you suggested out and it worked. Thank you very much!