What is the difference of using ; after end?

Hi, dear all,

For example, if I write a if loop, after end, what is the difference if I use ;?

Thanks.

Answer 1

[Wayne King]

None, you don't need a semi-colon after an end statement. Putting a semi-colon in or leaving one off do not generate mlint warnings.

[C Zeng]

Thanks! So I do not need to add a ; after the loop.

[Walter Roberson]

I have seen reports in the past that having the semi-colon or not affected the optimizer in some situations.

[C Zeng]

Oh, really, can you show me the papers? Why it will affect computation?

[Walter Roberson]

I think the notes I saw were in the cssm newsgroup. Most likely written by Bruno, or Jan.

[C Zeng]

OK, but I think it is a minor issue for computation, because with or without ";" does not change a lot.

[Walter Roberson]

The timing difference that comes to mind was on the order of a factor of 10 for the testcase that was used. As the internal mechanism that causes the issue is not well understood (at least not to us on the outside of Mathworks), it is not currently possible to predict whether the difference would scale with number of iterations or with work done in each iteration or if it was more or less a constant delay that could effectively be amortized.

Answer 2

[Daniel Shub]

I often add a semicolon or comma after statements like "end" where they are not strictly useful so that I can easily create single line commands. This is especially true when trying to answer questions on Answers

For example, you need a semicolons/commas to make the following work

for ii = 1:10, end;  ii

[C Zeng]

Makes sense.