Problem 43610. nanoseconds passed today

Created by Marc Jakobi

Solve Later

{"relationships":[{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/document","relationshipId":"rId1","target":"/matlab/document.xml"},{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/output","relationshipId":"rId2","target":"/matlab/output.xml"}],"parts":[{"partUri":"/matlab/document.xml","relationship":[],"contentType":"application/vnd.mathworks.matlab.code.document+xml","content":"<?xml version=\"1.0\" encoding=\"UTF-8\"?><w:document xmlns:w=\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\"><w:body><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Calculate the amount of nanoseconds passed in the current day of a certain date string.</w:t></w:r></w:p></w:body></w:document>"},{"partUri":"/matlab/output.xml","contentType":"text/xml","content":"<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\" ?><embeddedOutputs><metaData><evaluationState>manual</evaluationState><layoutState>code</layoutState><outputStatus>ready</outputStatus></metaData><outputArray type=\"array\"/><regionArray type=\"array\"/></embeddedOutputs>"}]}

Solve

Solution Stats

51 Solutions
12 Solvers

Last Solution submitted on Mar 19, 2021

Last 200 Solutions

Problem Comments

3 Comments

3 Comments

goc3 on 5 Dec 2016

The test suite has been expanded and fixed.

William on 28 Dec 2018

The date string identifies the date and time to the nearest second, so we know that the last 9 digits of the correct number of nanoseconds have to be zeros. Where are these odd, fractional numbers coming from?

Rafael S.T. Vieira on 4 Sep 2020

We must use the function datenum to obtain the necessary data. However it is still a phony data obtained by the roundup error of dividing the number of hours by 24. For instance, 20h10 becomes 20/24 + 10/60/24 (but this decimal data has nothing to do with the passed nanoseconds of a day; it's just the best floating point representation of this fraction). The correct would be to use a dot after the seconds like '20:10:00.123' for quantities smaller than 1 second. And no dot or zeros would mean 20*3600 + 10*60 seconds.

PS: If we use datevec(now), then we may see how nanoseconds are truly displayed,, and what data is currently missing from the test suite.

Solution Comments

Solution 2909389

2 Comments

2 Comments

Rafael S.T. Vieira on 4 Sep 2020

Here is a solution based on the error.

Rafael S.T. Vieira on 4 Sep 2020

For instance 73587999999895.69 is in fact 73588000000000, but since we are extracting data from converting fractional days to nanoseconds (two numbers of completely different order of magnitude, we get the error of 104.3125).

Solution 2909341

1 Comment

1 Comment

Rafael S.T. Vieira on 4 Sep 2020

Sorry, it was not clear how to obtain these numbers from the available data.

Problem Recent Solvers12

Problem Tags

datenum nanoseconds time

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Problem 43610. nanoseconds passed today

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers12

Suggested Problems

More from this Author15

Problem Tags

Community Treasure Hunt

Problem 43610. nanoseconds passed today

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers12

Suggested Problems

More from this Author15

Problem Tags

Community Treasure Hunt

Players