Matlab trying to access index zero of a matrix, even though the boundaries are specified!

Question

Philip 2014-10-15

0
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https://ww2.mathworks.cn/matlabcentral/answers/158684-matlab-trying-to-access-index-zero-of-a-matrix-even-though-the-boundaries-are-specified

评论： Philip 2014-10-15

Hi! I have this Matlab problem that's driving me crazy! I'm trying to get values from a matrix and use these in other functions, but Matlab is giving me errors that doesn't make any sense. Here's the code: (R,W,T and v0 are constants declared in the beginning of the code. [t,x] returns t as a 81x1 matrix, and x as a 81x4 matrix).

[t,x]=ode45(@func2,[0 T],[0;v0;0;0]);
r=@(i)R-x(i,1);
fi=@(i)W*t(i)+(x(i,2));
er=@(alpha)[cos(alpha);sin(alpha)];
for i=1:length(t)
   RV(i,:)=R*er(W*t(i));
   RD(i,:)=r(t(i))*er(fi(i));
end
for i=1:length(t)
   RB(i)=abs(RV(i,:)-RD(i,:));
end
plot(RB)

Here's the problem: When I run this i get the error:

"Attempted to access x(0,1); index must be a positive integer or logical.

Error in @(i)R-x(i,1)"

Even though it is specified in the for-loops that the value of i should start with 1. Declaring i as a variable with the value 1 doesn't help, neither does changing the name from i to something else in the functions before the for-loops. I don't understand why it is trying to access index 0!

Would greatly appreciate any help i can get!