MATLAB: Array Indexing, Array within an Array

arrayindexindexingMATLABmatricesmatrixmatrix arrayvariable

I need help understanding how this code works.

Consider the variables B = [1 5 8] and D = [1; 1; 1]. When I write the code B(D,:) I am getting the output of [1 5 8; 1 5 8; 1 5 8] and I am not sure why.

Please be thorough in your explination.

Thanks for the help.

Best Answer

Because, by definition,

 B(D,:) = [   B(D(1),:)   ;  B(D(2),:) ; B(D(3),:) ]
     
        = [   B(1,:)   ;  B(1,:) ; B(1,:) ]
        
        = [1 5 8; 1 5 8; 1 5 8]

Related Solutions

MATLAB: N=A(B) where A and B are matrices

A(B) returns the value of the B(ith) element of A. The elements are counted column-wise, what means than in your case: A(1) = 1; A(2) = 4; A(3) = 2; A(4) = 8; A(5) = 3; ... A(18) = 8;

Now, if you take the matrix B as index, you get back a matrix whose elements are the elements of A in the position determined by the value of the element of B:

B(1) = 5

then, the first element of A(B) = A(5) = 3.

B(2) = 9

then, the second element of A(B) = A(9) = 3

B(3) = 1

then, the second element of A(B) = A(1) = 1

and so on.

MATLAB: Regarding the matrix indexing,

Hello,

How about if you modify your function like this

function T = Euler_explicit(T_0, L, P,C, h)
A = inv(C)*L;           % Conductance and inverse of specific heat capacity
b = inv(C)*P;           % Power loss vector and inverse of specific heat capacity          
   f_1 = f(A, b, T_0);            % Calling the differential equation function
   T = T_0 + f_1*h;   %here I need to change the indexing, but I am not getting how to change it to get one row vector for each iteration _this is second question
end

Best Answer

Related Solutions

MATLAB: N=A(B) where A and B are matrices

MATLAB: Regarding the matrix indexing,

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