I need help plotting

I don't know where the problem is. I can't get it to plot like this:

This is the code

clear
close all
Z1=500;
Z2=50;
Z3=500;
u=1;
tau1=(2*Z2)/(Z1+Z2);
tau2=(2*Z1)/(Z1+Z2);
tau3=(2*Z3)/(Z3+Z2);
p1=(Z2-Z1)/(Z2+Z1);
p2=(Z1-Z2)/(Z1+Z2);
p3=(Z3-Z2)/(Z3+Z2);
T=2*10^-6;
t=0:50*T/200:50*T;
% a voltage
n=linspace(2,25,length(t));
ua1=tau1*u.*(t>=0);
Uan=(tau1.*tau2.*(p3.^n-1).*(p2.^n-2).*u).*(t>=(n-1)*2*T);
% b voltage
n=linspace(1,25,length(t))
uab=(tau1.*tau3.*(p3.^n-1).*(p2.^n-1).*u).*(t>=n*2*T-T)
syms n % declare n as symbolic variable 
F1=symsum(Uan,n,2,25);
F2=symsum(uab,n,1,25)
figure(1)
plot(t,F1+ua1, 'DisplayName', 'F1')
hold on
plot(t,F2, 'DisplayName', 'F2')
hold off

It plots like this:

And it should plot like this

Does anyone know how to fix this?I just started studying matlab and can't find an answer for it. Many thanks.

[Jason Shrand]

I think part of the issue is this line of code here:

Uan=(tau1.*tau2.*(p3.^n-1).*(p2.^n-2).*u).*(t>=(n-1)*2*T);

and

uab=(tau1.*tau3.*(p3.^n-1).*(p2.^n-1).*u).*(t>=n*2*T-T)

I think you need parentheses around your exponents, like below:

Uan=(tau1.*tau2.*(p3.^(n-1)).*(p2.^(n-2)).*u).*(t>=(n-1)*2*T);

and

uab=(tau1.*tau3.*(p3.^(n-1)).*(p2.^(n-1)).*u).*(t>=n*2*T-T)

It still doesn't look like your picture, but maybe it's a step closer

Answer 1

[Mathieu NOE]

hello

this is the correct code

Uan and Uab needs to be 2D arrays (n rows and columns as many as length(t))

also some missing parenthesis as also found by @Jason Shrand

then its fairly straigthforward to do a (one direction) sum (without any need to sym operations)

clear
close all
Z1=500;
Z2=50;
Z3=500;
u=1;
tau1=(2*Z2)/(Z1+Z2);
tau2=(2*Z1)/(Z1+Z2);
tau3=(2*Z3)/(Z3+Z2);
p1=(Z2-Z1)/(Z2+Z1);
p2=(Z1-Z2)/(Z1+Z2);
p3=(Z3-Z2)/(Z3+Z2);
T=2*10^-6;
t=0:50*T/200:50*T;
% a voltage
n=(2:25)';
ua1=tau1*u.*(t>=0);
Uan=(tau1*tau2*(p3.^(n-1)).*(p2.^(n-2))*u).*(t>=(n-1)*2*T);
% b voltage
n=(1:25)';
uab = (tau1*tau3*(p3.^(n-1)).*(p2.^(n-1))*u).*(t>=n*2*T-T);
F1=sum(Uan,1);
F2=sum(uab,1);
figure(1)
plot(t,F1+ua1, 'DisplayName', 'F1')
hold on
plot(t,F2, 'DisplayName', 'F2')
hold off

[Mircea Prisada]

Your answer is easier to understand, thanks.

[Mathieu NOE]

as always, my pleasure !

Answer 2

[Alan Stevens]

More like this perhaps:

Z1=500;
Z2=50;
Z3=500;
u=1;
tau1=(2*Z2)/(Z1+Z2);
tau2=(2*Z1)/(Z1+Z2);
tau3=(2*Z3)/(Z3+Z2);
p1=(Z2-Z1)/(Z2+Z1);
p2=(Z1-Z2)/(Z1+Z2);
p3=(Z3-Z2)/(Z3+Z2);
T=2*10^-6;
t=0:50*T/200:50*T;
% a voltage
n1=2:25;
ua1= @(t) tau1*u.*(t>=0);
% b voltage
n2=1:25;
uab= @(t)sum((tau1.*tau3.*p3.^(n2-1).*p2.^(n2-1).*u).*(t>=(n2*2*T-T)));

figure(1)
plot(t,ua1(t) + Uanfn(n1,t,tau1,tau2,p2,p3,u,T), 'DisplayName', 'F1')
hold on
plot(t,uabfn(n2,t,tau1,tau3,p2,p3,u,T), 'DisplayName', 'F2')
hold off

function Uan = Uanfn(n,t,tau1,tau2,p2,p3,u,T)
         
         Uan = 0;
         for i = 1:numel(n)
             Uan = (tau1.*tau2.*p3.^(n(i)-1).*p2.^(n(i)-2).*u).*(t>=(n(i)-1)*2*T) + Uan;
         end

end

function uab = uabfn(n,t,tau1,tau3,p2,p3,u,T)

         uab = 0;
         for i = 1:numel(n)
            uab = (tau1.*tau3.*p3.^(n(i)-1).*p2.^(n(i)-1).*u).*(t>=(n(i)*2*T-T)) + uab;
         end
end