Plotting graph of negative values of array in integral2 with 3 variables
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Cem Tuncer
am 7 Apr. 2019
Bearbeitet: dpb
am 7 Apr. 2019
I am new with Matlab please help me regarding plotting a graph of double integral with respect to third variable. The third variable is an angle, in range of -80 to 80 degrees. I want to plot the graph also for negative values but, matlab does not allow negative indices of matrix. The last version of the code is as follows, but it does not give the solution of negative values of n as I want, just shifting z values of 1:numel(n) to -80 to 80.
u0= 4*pi*10.^-7;N1 = 15; N2 = 15 ; L1 = 8.215*10.^-6;L2 = 8.215*10.^-6;
r1 = 0.03; r2=0.03; d=0.1; yaxis=0;
K1 =(N1.*N2.*u0)./(4.*pi.*sqrt(L1.*L2))
n=-80:80;
ktheta=zeros(size(n))
for z=1:numel(n)
fun=@(x,y,z)(r1.*r2.*sin(x).*sin(y)+r1.*r2.*cos(x).*cos(y).*cosd(z))./sqrt((r1.^2)+(r2.^2)+(yaxis.^2)+(d.^2)-2.*r1.*y.*sin(x)-2.*r1.*r2.*cos(x).*cos(y)+(2.*r2.*y.*sin(y)-2.*r1.*r2.*sin(x).*sin(y)).*cosd(z)+2.*r2.*d.*sin(y).*sind(z));
ktheta(z) = K1*integral2(@(x,y)fun(x,y,z),0,2*pi,0,2*pi)
end
plot(n,ktheta)
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Akzeptierte Antwort
madhan ravi
am 7 Apr. 2019
Bearbeitet: madhan ravi
am 7 Apr. 2019
Not sure what you are trying to do but see if the below does what you want:
u0= 4*pi*10.^-7;
N1 = 15;
N2 = 15 ;
L1 = 8.215*10.^-6;
L2 = 8.215*10.^-6;
r1 = 0.03;
r2=0.03;
d=0.1;
yaxis=0;
K1 =(N1.*N2.*u0)./(4.*pi.*sqrt(L1.*L2));
z=-80:80;
ktheta=zeros(size(n));
fun=@(x,y,z)(r1.*r2.*sin(x).*sin(y)+r1.*r2.*cos(x).*cos(y).*cosd(z))./sqrt((r1.^2)+(r2.^2)+(yaxis.^2)+(d.^2)-2.*r1.*y.*sin(x)-2.*r1.*r2.*cos(x).*cos(y)+(2.*r2.*y.*sin(y)-2.*r1.*r2.*sin(x).*sin(y)).*cosd(z)+2.*r2.*d.*sin(y).*sind(z));
for k=1:numel(n)
ktheta(k) = K1*integral2(@(x,y)fun(x,y,z(k)),0,2*pi,0,2*pi)
end
plot(z,ktheta)
Weitere Antworten (1)
dpb
am 7 Apr. 2019
Bearbeitet: dpb
am 7 Apr. 2019
- The functional is invariant upon the the loop; remove the definition from inside the loop
- Use meaningful name for the degrees array; then won't confuse data with loop indices so easily
- Loop over the array, don't use data arrays as looping indices:
u0= 4*pi*10.^-7;N1 = 15; N2 = 15 ; L1 = 8.215*10.^-6;L2 = 8.215*10.^-6;
r1 = 0.03; r2=0.03; d=0.1; yaxis=0;
K1 =(N1.*N2.*u0)./(4.*pi.*sqrt(L1.*L2))
dg =-80:80;
ktheta=zeros(size(dg),1);
fun=@(x,y,z)(r1.*r2.*sin(x).*sin(y)+r1.*r2.*cos(x).*cos(y).*cosd(z))./ ...
sqrt((r1.^2)+(r2.^2)+(yaxis.^2)+(d.^2)- ...
2.*r1.*y.*sin(x)-2.*r1.*r2.*cos(x).*cos(y)+ ...
(2.*r2.*y.*sin(y)-2.*r1.*r2.*sin(x).*sin(y)).*cosd(z)+2.*r2.*d.*sin(y).*sind(z));
for i=1:numel(dg)
ktheta(i) = K1*integral2(@(x,y)fun(x,y,dg(i)),0,2*pi,0,2*pi);
end
plot(dg,ktheta)
You have an issue in the functional in that over the range of 0:2*pi for the y argument, it returns complex values. I didn't try to dig into such a lot of stuff to try to figure out which term, specifically is the culprit, but
>> fun(0,0:2*pi,-80)
ans =
0.0016 + 0.0000i 0.0007 + 0.0000i -0.0004 + 0.0000i -0.0012 + 0.0000i 0.0000 + 0.0009i 0.0000 - 0.0002i 0.0000 - 0.0020i
>> fun(0,0:pi,-80)
ans =
0.0016 0.0007 -0.0004 -0.0012
>>
2 Kommentare
dpb
am 7 Apr. 2019
Bearbeitet: dpb
am 7 Apr. 2019
"It strangely work[s] with variable z, instead of dg,"
Oh! Indeed; I neglected to change the z variable in the anonymous function. The z vector is built into the function detinition when it is defined and so needed
fun=@(x,y,z)(r1.*r2.*sin(x).*sin(y)+r1.*r2.*cos(x).*cos(y).*cosd(dg))./ ...
sqrt((r1.^2)+(r2.^2)+(yaxis.^2)+(d.^2)- ...
2.*r1.*y.*sin(x)-2.*r1.*r2.*cos(x).*cos(y)+ ...
(2.*r2.*y.*sin(y)-2.*r1.*r2.*sin(x).*sin(y)).*cosd(dg)+2.*r2.*d.*sin(y).*sind(dg));
It was that oversight that caused the imaginary result..so, in the end, it's the same fix as madhan's...
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