addtodate creates too many milliseconds

Question

d_moan 2016-8-3

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/298244-addtodate-creates-too-many-milliseconds

评论： d_moan 2016-8-28

采纳的回答： Azzi Abdelmalek

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I wanted to create a vector of all milliseconds in a day, so I wrote

0:addtodate(0,1,'millisecond'):(1-addtodate(0,1,'millisecond'));

which resulted in a vector with 86767016 elements, instead of the expected 24*60*60*1000 = 86400000 ones.

The same with seconds worked just fine.

I assume this is due to some roundoff error, and of course I could just write (0:86400000-1)/86400000, but I was wondering if this should be considered a bug.

Also was wondering what would be the better approach in the future when adding several milliseconds - I can think of three options:

addtodate(0,1,'millisecond') + addtodate(0,1,'millisecond');
2*addtodate(0,1,'millisecond');
2/86400000;

(The last one giving a different result than the first two)

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Answer 1

Azzi Abdelmalek 2016-8-3

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https://ww2.mathworks.cn/matlabcentral/answers/298244-addtodate-creates-too-many-milliseconds#answer_230639

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Use linspace

a=linspace(0,1-addtodate(0,1,'millisecond'),86400000);

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Steven Lord 2016-8-3

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Or colon:

msPerDay = milliseconds(days(1));
y = milliseconds(0:1:msPerDay-1);

d_moan 2016-8-28

Hey guys, thanks for the quick responses, sorry for my belated one.

@Steven, looks like a great option, but unfortunately I can't use it due to my Matlab version. Also, had you opened it as a different answer instead of a comment I could've at least upvoted it.

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