How to plot a math function with a vector

Hello everbody,

I have a problem with a task. I've read an excel data into matlab and worked with this data. As i made an integral with the values of my excel data, i now have to take those values and make a math function as following : Zth = (Tmax - T_j) / P. I dont know how to implimate that vector of T_j into the function and generate a plot out of it.

Best regards

David

clear all;
close all;
clc;
 
values = xlsread('Beispiel-Kurven', 'Fit 0');
 
cooling_time = values(:,1)';
 
R_F = values(:,4);
R_F = R_F(~isnan(R_F))';
 
C_F = values(:,5);
C_F = C_F(~isnan(C_F))';
 
dZ_th = @(t) 0;
for v = 1:length(R_F)
dZ_th = @(t) dZ_th(t) + exp(-t / (R_F(v) * C_F(v))) / C_F(v);
end
 
P = @(t) 10;
 
T_j_scalar_t = @(t) integral(@(tau) P(tau) * dZ_th(t - tau), 0, t);
T_j = @(t) arrayfun(T_j_scalar_t, t);

Tmax = values(1,2)

Zth =   (Tmax - T_j_scalar_t) / P

semilogx(cooling_time, Zth(cooling_time))
 
%semilogx(cooling_time, T_j(cooling_time))

[Torsten]

Is it really correct that you want dZ_th to be defined as

dZ_th(t) = sum_{v=1}^{v=N} exp( -t*( R_F(v) * C_F(v) ) ) / C_F(v);

where N = length(R_F) ?

[David Sicic]

yes

Answer 1

[Torsten]

Then maybe

T_j_scalar_t = @(t) integral(@(tau) P(tau) .* dZ_th(t - tau), 0, t);
T_j = arrayfun(@(t)T_j_scalar_t(t), cooling_time);
Tmax = values(1,2);
Zth =   (Tmax - T_j) ./ P(cooling_time);
semilogx(cooling_time, Zth)

[David Sicic]

omg, you made my day!!

Thank you so much, i lost a lot of hair trouble shooting that!!

[David Sicic]

Why did you exactly used ./ in the 4th line?

Could you explain that quickly?

[Torsten]

T_j and P(cooling_time) are vectors with the length of the array "cooling_time".

You want to divide them elementwise, thus ./ instead of /

Since P is a constant function, you could alternatively have used

Zth =   (Tmax - T_j) / P(cooling_time(1));

[David Sicic]

Great, thank you for your time and explanation!