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# How to fix looping?

Asked by Devia Rafika Putri on 15 May 2013

this is my program:

v = 120;

r1 = 1.8;

x1 = 2.4;

r2 = 3.5;

x2 = 1.2;

xm = 60;

ns = 1800;

ws = 188.5;

s = (0.5:1:50)/50;

s (1) = 0.0001;

nm = (1-s)*ns;

for i = 1:51;

zf(i) =(((r2/s(i))+(j*x2))*(j*xm))/(((r2/s(i))+(j*x2))+(j*xm));

zb(i) = (((r2/(2-s(i)))+(j*x2))*(j*xm))/(((r2/(2-s(i)))+(j*x2))+(j*xm));

I(i) = v/(r1+(j*x1)+(0.5*zf(i))+(0.5*zb(i)));

PagF(i) = (abs(I(i)^2))*(0.5*real(zf(i)));

PagB(i) = (abs(I(i)^2))*(0.5*real(zb(i)));

Pag(i)=PagF(i)-PagB(i);

Tind(i) = Pag(i)/ws;

end

figure (1);

plot(nm,Tind,'Color','b','LineWidth',2.0);

grid on;

hold off;

*but after i run this program an error occurred with argument: Attempted to access s(51); index out of bounds because numel(s)=50.

Error in ==> fasbel3 at 15 zf(i) =(((r2/s(i))+(j*x2))*(j*xm))/(((r2/s(i))+(j*x2))+(j*xm));

Devia Rafika Putri on 15 May 2013

thanks a lot craig.. craig are u an electrical engineer., i hv a more problem..

Craig Cowled on 15 May 2013

Devia, Andrei's code is much neater. No need for a loop, just use element wise divide './'. And no, I'm not an electrical engineer. I'm a structural engineer working on experimental structural dynamics problems.

Devia Rafika Putri on 15 May 2013

ok craig.. i see.. but some code from andrei, i still dont understand.. but i'll find it..

ooh, I thought you were an electrical engineer

because I'm having problems with programs relating to single phase motor..

thanks so much craig..you are very helpful..

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Answer by Andrei Bobrov on 15 May 2013
Edited by Andrei Bobrov on 15 May 2013
```v = 120;
r1 = 1.8;
x1 = 2.4;
r2 = 3.5;
x2 = 1.2;
xm = 60;
ns = 1800;
ws = 188.5;
```
```s = [.0001;(.5:50).'/50];
s1 = [2-s,s];
z =(r2./s1+1i*x2)*1i*xm./( r2./s1+1i*(x2+xm) );
I = v./(r1+1i*x1+mean(z,2));
Tind = diff(bsxfun(@times,abs(I.^2),real(z)*.5),1,2)/ws;
```
```plot((1-s)*ns,Tind,'Color','b','LineWidth',2.0);
grid on;
```

Devia Rafika Putri on 15 May 2013

your program is work, thanks so much andrei!!! but there is some code that i dont understand..

s = [.0001;(.5:50).'/50];

s1 = [s, 2-s];

Tind = -diff(bsxfun(@times,abs(I.^2),real(z)*.5),1,2)/ws;

what that means? can you explain?? thanks before..

with sincerity Devia

Andrei Bobrov on 15 May 2013

Hi Devia!

Rewrite code:

```s = [.0001;(.5:50).'/50];
s1 = [2-s,s];
z =(r2./s1+1i*x2)*1i*xm./( r2./s1+1i*(x2+xm) );
I = v./(r1+1i*x1+mean(z,2));
Tind = diff(bsxfun(@times,abs(I.^2),real(z)*.5),1,2)/ws;
```

as:

```s = [.0001;(.5:50).'/50];
s1 = [2-s,s];
z =(r2./s1+1i*x2)*1i*xm./( r2./s1+1i*(x2+xm) );
I = v./(r1+1i*x1+mean(z,2));
Ia2 = abs(I.^2);
r = real(z)*.5;
P = bsxfun(@times,Ia2,r); % as in your code: P = [PagB PagF];
Pag = diff(P,1,2); % as Pag = PagF - PagB;
Tind = Pag/ws;
```
Devia Rafika Putri on 15 May 2013

Hi Andrei, thank you so much for your explain.. i'm so grateful.

but actually I have another problem. is about 1 phase motors, can you help me?

if you can, I will send my problem to your email..

thanks so much, Andrei..

with sincerity Devia

Answer by Yao Li on 15 May 2013

It seems the length of array s is 50, but you wanna call s(51) in the for loop

Devia Rafika Putri on 15 May 2013

thanks a lot Yao Li.. its work.. are you an electrical engineer? i hv a more problem..

Yao Li on 15 May 2013

Sometimes, I act as an electrical engineer. lol.

Pls. feel free to contact me if u have other questions. Email preferred.

Devia Rafika Putri on 15 May 2013

lol.. thanks so much Yao li, I've sent an email to you .. if you're not busy please check it..