"Index exceeds the number of array elements"
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Hello,
I am recieving this error:
Index exceeds the number of array elements (1).
Error in sym/subsref (line 890)
R_tilde = builtin('subsref',L_tilde,Idx);
Error in E_field (line 7)
Ey = matlabFunction(E(2));
Here is the function file the error is referencing:
function [Ex, Ey, Ez] = E_field()
syms x y z
R_s = 0.02;
V = 0;
epnaut = 8.854187E-12;
k = 1/(4*pi*epnaut);
Q = (V*R_s)/k;
r = [x, y, z];
E = (k*Q/norm(r)^3)*r;
Ex = matlabFunction(E(1));
Ey = matlabFunction(E(2));
Ez = matlabFunction(E(3));
end
1 个评论
Walter Roberson
2020-1-29
The posted code works for me. However you should using the 'vars' option of matlabFunction or else your function handle is not going to accept any arguments because your R values are all constants.
采纳的回答
Matt J
2020-1-29
编辑:Matt J
2020-1-29
Perhaps this is what you are looking for,
function [Ex, Ey, Ez] = E_field(x,y,z)
R_s = 0.02;
V = 0;
epnaut = 8.854187E-12;
k = 1/(4*pi*epnaut);
Q = (V*R_s)/k;
r = [x, y, z];
E = (k*Q/norm(r)^3)*r;
Ex = E(1);
Ey = E(2);
Ez = E(3);
end
9 个评论
Walter Roberson
2020-2-1
Is there a reason you are using global instead of persistent ? Is there some other function that will use the created Bx By Bz Ex Ey Ez ?
更多回答(1 个)
Walter Roberson
2020-2-1
V = 0;
V is 0.
Q = (V*R_s)/k;
V is 0, so Q will be 0.
E = (k*Q/norm(r)^3)*r;
Provided that norm(r ) is not 0 and k is not infinity, then because Q is 0, E is going to be
zeros(size(r))
symvar() of a vector of 0 is empty. matlabFunction() of a constant, when you do not use any 'vars' option, is a function handle that accepts no inputs and returns a scalar copy of the constant.
The original code that was posted does not give me an index exceeded matrix dimension when I test it in R2019a.
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