Unclear array operation in matlab

Dear all, I have created a 5 * 3 array, named as 'conn' and another array as lm which is 1*2 as underneath:

conn= [1 5 6; 2 5 7; 3 4 5 ; 4 5 7; 5 6 8];

lm = [4 ,3];

conn(lm)

while running the code, it gives me the following output.

ans =

4 3

this operation with "conn(lm)" is totally unclear to me when I operate on 5*3 array. I will be grateful if anyone please help me to understand this code.

Answer 1

[Chunru]

conn= [1 5 6; 2 5 7; 3 4 5 ; 4 5 7; 5 6 8]

conn = 5×3

1 5 6 2 5 7 3 4 5 4 5 7 5 6 8

lm = [4 ,3];

% The following use lm as "linear" index to reference to conn
% The "linear" index count column by column
% so the 4th element of conn is (4,1)
conn(lm) 

ans = 1×2

4 3

conn(10)   % (5,2)th element of conn

ans = 6

[Himanshu]

Thank you very much. This was helpful and precise.

Answer 2

[weikang zhao]

Hello, this is matlab's unique indexing mechanism. For a 5*3 matrix, you can use 1-15 to index all elements.

Matlab uses column-major order, so your code is the same as the result below.

coon=[1 2 3 4 5 5 5 4 5 6 6 7 5 7 8];

lm=[4 3];

The output results are organized as follows

conn(lm)=[coon(4) coon(3)]=[4 3]

Incorrect use of '=' operator. Assign a value to a variable using '=' and compare values for equality using '=='.

Error in connector.internal.fevalMatlab

Error in connector.internal.fevalJSON

[Himanshu]

Thank you very much