What is the answer of [(4 -2 ) /2 , 5 +6 , 7 , 8 ] ? Why does MATLAB output [1 5 6 7 8]？

When the plus sign is preceded by a blank space：

 [(4 -2 ) /2 , 5 +6 , 7 , 8 ]

ans = 1×5

1 5 6 7 8

Delete blank space：

 [(4 -2 ) /2 , 5+6 , 7 , 8 ]

ans = 1×4

1 11 7 8

I don't understand why MATLAB will output different results.

Under normal circumstances, shouldn't spaces be ignored？

Answer 1

[VBBV]

     [5 +6]

Is not equivalent to

5+6

When you use concatenate operator [ ]

[VBBV]

But it's same when you use ( )

(5 +6)

Is equivalent to

5+6

[qqffssxx]

yes ~ great ~ thanks

Answer 2

[qqffssxx]

I got it!

[1 +3 +5 ] == [1 3 5]

Answer 3

[Askic V]

In Matalb, when you define an array (or vector) you can use the following syntax:

v = [1 3 4 5 6]

v = 1×5

1 3 4 5 6

This is exactly the same as:

v = [1, 3, 4, 5, 6] 

Answer 4

[Steven Lord]

See this documentation page for more information.

[Stephen23]

There is nothing on that page that explicitly explains how space is interpreted around arithmetic operators when building arrays:

[1 - 2]

ans = -1

[1 -2]

ans = 1×2

1 -2

This topic comes up fairly regularly on Answers, indicative of confusion regarding this topic, and that page looks like a good place to document it. None of the other "obvious" pages I found in a quick search now covered this topic either, e.g.:

https://www.mathworks.com/help/matlab/math/creating-and-concatenating-matrices.html