Index exceeds matrix dimensions

Question

Azza Ahmed 2012-1-5

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/25408-index-exceeds-matrix-dimensions

Hello,

I think I have a problem with my matrices but I can't figure out where to fix it. I am trying to read a text file of size 28179*6. The code that I have written is:

clear all
[A,B] = freeprecess(dT,T1,T2,df);
M = zeros(3,N);
M(:,1) = [0;0;1];    
M(:,2)= throt(abs(Rflip(1)),angle(Rflip(1))) * M(:,1);           % 
M(:,3)=A*M(:,2)+B;
importfile ('allgradients.txt');  % here I am importing the file
Gz = data(:,5);
F = length(data(:,5));
for s = 1:F
M(:,s)=A*M(:,s)+B;
gradSlsel = Gamma*2*pi*(dT/1000)*Gz(s)*1.7507;  
M = zrot(gradSlsel)*M;
time = [0:F]*dT;
plot(time,M(1,:),'b-',time,M(2,:),'r--',time,M(3,:),'g-.');
legend('M_x','M_y','M_z');
xlabel('Time (ms)');
ylabel('Magnetization');
axis([min(time) max(time) -1 1]);
grid on;
end;

The message that I get is "Index exceeds matrix dimension". As I can see dim of Gz is the same as time. So where would be the problem and how can I fix it?

Would you kindly help me with this?

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Answer 1

Walter Roberson 2012-1-5

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https://ww2.mathworks.cn/matlabcentral/answers/25408-index-exceeds-matrix-dimensions#answer_33330

Your time vector is one longer than Gz is.

Your code assumes that M is the same length as time, but M could be larger since M is initialized as 3 by N and we do not know the relationship between N and F.

Note that if N is smaller than F, then M grows inside the loop and so will not be the same size as the fixed-length "time"