How do you round up or down to a decimal

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Ted H
Ted H 2023-1-2
编辑： Ted H 2023-1-3
I want to round UP to a specific decimal location (tenths in my current need).
I am getting errors using round():
a = 6.234;
b = round( a, 1);
gives 6.2. It works, but is not UP. It rounded DOWN. So I add TieBreaker:
b = round( a, 1, TieBreaker="plusinf");
gives
Error using round
Too many input arguments.
I missed something
b = round( a, TieBreaker="plusinf");
gives
Error using round
Third input must be either 'decimals' or 'significant'.
I missed something
Any comments, corrections, alternate methods are appreciated.

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采纳的回答

Image Analyst
Image Analyst 2023-1-2
编辑：Image Analyst 2023-1-2
To round up use ceil
To round down use floor
  2 个评论
Ted H
Ted H 2023-1-3
I don't see in ceil where you can handle the decimal. I see the time component only.
Voss
Voss 2023-1-3
编辑：Voss 2023-1-3
Ran in:
You can do this kind of thing:
a = 6.234;
% round UP to the tenths:
b = ceil(a*10)/10
b = 6.3000
a = 6.237;
% round DOWN to the hundredths:
b = floor(a*100)/100
b = 6.2300

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更多回答（1 个）

John D'Errico
John D'Errico 2023-1-2
编辑：John D'Errico 2023-1-2
Ran in:
You are trying to use capabilities of round that are not present in your (older) MATLAB release.
For that code to work, you need to upgrade to a current release. But a simple call to round should still work for you.
b = round(6.234,1)
b = 6.2000
c = round(6.253,1)
c = 6.3000
Just that the option you are trying to use is a more recent capability.
  3 个评论
显示 1更早的评论
John D'Errico
John D'Errico 2023-1-2
I am constantly being surprised, since I too often forget to read the release notes for every release.
Ted H
Ted H 2023-1-3
编辑：Ted H 2023-1-3
Rereading the matlab documentation, tiebreaker is only for the exact midpoint. So there is no round up or round down. This does not solve my problem. @Image Analyst solution does work, however a minor complaint is that it reduces readability (IMO).
Unrelated to the technique, I would have thought rounding up or down to a specific decimal place was a need, but I suppose not, or it was resolved by users dividing and multiplying. Matlab was first commercialized in the 80s, and not until 2014 was this need made a function, while this is standard in many other programs.
@John D'Errico your solution is just rounding. not rounding always up or always down to a specific decimal place. I might not have made this as clear as I should have. I edited the original post.

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