extract data from a loop

Hi Guys,

Can any body help on how extract and plot data from this?

clc
clear
close all
format long
mu0=4*pi*10^-7;
R=0.9;
N=17;
I=12.5;
for z=-1.5:0.01:1.5;
    B1=((mu0*N*I*R^2)/2)*(1/(R^2+(z+(R/2))^2)^(3/2));
    B2=((mu0*N*I*R^2)/2)*(1/(R^2+(z-(R/2))^2)^(3/2));
    Bt=B1+B2;
    figure(1)
    plot(z,B1); hold on;grid on
    plot(z,B2); hold on;grid on
    plot(z,Bt); hold on;grid on
end

Answer 1

[Shubhankar Poundrik]

Hi Oday,

I understand that you are finding difficulty in keeping each value of the variables generated in the loop saved. Additionally, the plot generated by your code is blank and does not show the plots.

Data created in a loop can be extracted by saving it to an array. The entire data can then be plotted from the array itself, rather than plotting it point wise in the loop. The ‘hold on’ command may be used once before adding all the plots. Then the ‘hold off’ command should be used.

The below code may help.

clc
clear
close all
format long
mu0=4*pi*10^-7;
R=0.9;
N=17;
I=12.5;

z2 = -1.5:0.01:1.5;
elm = length(z2);
B1arr = zeros(1, elm); % creating array to add B1 to in the loop
B2arr = zeros(1, elm); % creating array to add B2 to in the loop
Btarr = zeros(1, elm); % creating array to add Bt to in the loop
i=1;
for z=-1.5:0.01:1.5
    B1=((mu0*N*I*R^2)/2)*(1/(R^2+(z+(R/2))^2)^(3/2));
    B2=((mu0*N*I*R^2)/2)*(1/(R^2+(z-(R/2))^2)^(3/2));
    Bt=B1+B2;
    B1arr(1,i ) = B1;  % adding B1 to array
    B2arr(1,i ) = B2;  % adding B2 to array
    Btarr(1,i ) = Bt;  % adding Bt to array
    i=i+1;
end

hold on
plot(z2, B1arr, 'b')
plot(z2, B2arr, 'r')
plot(z2, Btarr, 'g')
hold off

Regards,

Shubhankar

Answer 2

[KSSV]

clc
clear
close all
format long
mu0=4*pi*10^-7;
R=0.9;
N=17;
I=12.5;
Z=-1.5:0.01:1.5;
B1 = zeros(size(Z)) ; 
B2 = zeros(size(Z)) ; 
for i = 1:length(Z)
    z = Z(i) ; 
    B1(i)=((mu0*N*I*R^2)/2)*(1/(R^2+(z+(R/2))^2)^(3/2));
    B2(i)=((mu0*N*I*R^2)/2)*(1/(R^2+(z-(R/2))^2)^(3/2));
end
Bt = B1+B2 ; 
figure
hold on
plot(Z,B1,'r')
plot(Z,B2,'b')
plot(Z,Bt,'g')

Note that, there is no requirement of using a loop. You can achieve what you want without loop also.

clc
clear
close all
format long
mu0=4*pi*10^-7;
R=0.9;
N=17;
I=12.5;
z=-1.5:0.01:1.5;
B1=((mu0*N*I*R^2)/2)*(1./(R^2+(z+(R/2)).^2).^(3/2));
B2=((mu0*N*I*R^2)/2)*(1./(R^2+(z-(R/2)).^2).^(3/2));

Bt = B1+B2 ; 
figure
hold on
plot(z,B1,'r')
plot(z,B2,'b')
plot(z,Bt,'g')

[madhan ravi]

? Wasn't that edited after I added my answer?

[KSSV]

What do you think?

[madhan ravi]

xD

Answer 3

[madhan ravi]

No loops needed:

mu0=4*pi*10^-7;
R=0.9;
N=17;
I=12.5;
z=-1.5:0.01:1.5;
B1=((mu0*N*I*R^2)/2).*(1./(R^2+(z+(R/2)).^2).^(3/2));
B2=((mu0*N*I*R^2)/2).*(1./(R^2+(z-(R/2)).^2).^(3/2));
Bt=B1+B2;
figure(1)
plot(z,B1,'k')
hold on
grid on
plot(z,B2,'b')
plot(z,Bt,'m')

Answer 4

[Oday Shahadh]

Hi Guys,

Is there any way to accept all your answers? you all great, really appreciated