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MINATI
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Subscripted assignment dimension mismatch.

Asked by MINATI
on 18 May 2019
Latest activity Commented on by Walter Roberson
on 20 May 2019
function main
D=1; %L=0;
Pr=1;R=0.1;Sc=1;
xa=0;xb=6;
Lv = [-2.5:0.025:0];
p = [];
for i=1:length(Lv)
L = Lv(i);
fODE = @(x,y) [y(2); y(3); y(2)^2-y(3)*y(1)-1; y(5); -3*Pr*y(1)*y(5)/(3+4*R); y(7); -Sc*y(1)*y(7)];
BCres= @(ya,yb)[ya(1); ya(2)-L-D*ya(3); ya(4)-1; ya(6)-1; yb(2)-1; yb(4);yb(6)];
xint=linspace(xa,xb,101);
solinit=bvpinit(xint,[0 1 0 1 0 1 0]);
sol=bvp4c(fODE,BCres,solinit);
sxint=deval(sol,xint);
%%WE NEED TO PLOT for
S(i,1)=sxint(3,:);
end
figure(1)
plot(Lv,S,'-','Linewidth',1.5);
xlabel('\bf \lambda');
ylabel('\bf C_{f}');
hold on
end
%%While running the code following ERROR occurs:
Subscripted assignment dimension mismatch.
Error in (line 17)
S(i,1)=sxint(3,:);

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2 Answers

Answer by Walter Roberson
on 19 May 2019
 Accepted Answer

function all_sxint = main
D=1; %L=0;
Pr=1; R=0.1; Sc=1;
xa=0;xb=6;
Lv = [-2.5:0.025:0];
nLv = length(Lv);
all_sxint = cell(nLv, 1);
S = zeros(nLv, 7);
for i=1:nLv
L = Lv(i);
fODE = @(x,y) [y(2); y(3); y(2)^2-y(3)*y(1)-1; y(5); -3*Pr*y(1)*y(5)/(3+4*R); y(7); -Sc*y(1)*y(7)];
BCres= @(ya,yb)[ya(1); ya(2)-L-D*ya(3); ya(4)-1; ya(6)-1; yb(2)-1; yb(4);yb(6)];
xint=linspace(xa,xb,101);
solinit=bvpinit(xint,[0 1 0 1 0 1 0]);
sol=bvp4c(fODE,BCres,solinit);
sxint=deval(sol,xint);
all_sxint{i} = sxint;
S(i,:) = sxint(3,:);
end
figure(1)
plot(Lv, S, '-', 'Linewidth', 1.5);
xlabel('\bf \lambda');
ylabel('\bf C_{f}');
legend({'bc1', 'bc2', 'bc3', 'bc4', 'bc5', 'bc6', 'bc7'})
end
Assign the output to a variable so that you can examine all of the time points for all of the Lv values afterwards, as you indicate that you need to be able to do that.

  11 Comments

I noticed some oddities in the output. I used options to push the permitted mesh points way up, and zoomed in closer. It turns out there is something unusual going on at -2.4648 .
exception.png
Warning: Unable to meet the tolerance without using more than 500000 mesh points.
The last mesh of 292855 points and the solution are available in the output argument.
The maximum residual is 0.204915, while requested accuracy is 0.001.
The above was for Lv = linspace(-2.475, -2.425, 50);
The residual is staying pretty much the same as I increase the number of mesh points and zoom in more closely, which is potentially hinting at a singularity.
Different lines correspond to different xint.
No we cant go beyond \lambda = - 2
Lv = [-2.5:0.025:0]; is in your existing code

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Answer by Matt J
on 18 May 2019
Edited by Matt J
on 18 May 2019

sxint(3,:) is not a scalar, but the left hand side S(i,1) is a scalar location.

  8 Comments

@Matt J
For all values of sxint(3,:), what changes should be made in S(i,1) OR in Lv
i.e, we need for all values
Is there a reason you need to calculate at all of the time points, and then to store data for only the third time point? Is there a particular reason why my suggestion to calculate only at the third time point will not work for you?
Yes, Actually I need to validate a previous study with mine but unable. Since they have drawn with all points, I am trying in that way.

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