Problem 918. Find the repeating decimal pattern!

Created by Matt Fig

Solve Later

{"relationships":[{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/document","targetMode":"","relationshipId":"rId1","target":"/matlab/document.xml"},{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/output","targetMode":"","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\"?>\n<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>Write a function that takes one double input value and returns only the repeating decimal, if any, as a string. Only decimals for which</w:t></w:r><w:r><w:t> </w:t></w:r><w:r><w:rPr><w:b/></w:rPr><w:t>all</w:t></w:r><w:r><w:t> digits are part of the repeating pattern will be counted. (See the 3rd example below.) Inputs will be in the range [0 1].</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>If no repeating decimal is found, the function should return an empty string. Of course the repeating decimal may break down in the last bit due to floating point arithmetic, but we will ignore that.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Examples:</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[T = repeatingdec(7/11)  % Returns T = '63'\nT = repeatingdec(1/3)   % Returns T = '3'\nT = repeatingdec(5/6)    % Returns T = ''\nT = repeatingdec(0)      % Returns T = '0']]></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

91 Solutions
14 Solvers

Last Solution submitted on Oct 04, 2020

Last 200 Solutions

Problem Comments

2 Comments

2 Comments

Andrew Newell on 20 Jun 2013

The tests are inconsistent with the statement of the problem. Finite strings like ..123451234512345 only repeat to the end of the string, then switch to zeros.

Rafael S.T. Vieira on 4 Oct 2020 at 3:31

The problem should specify the precision required, there are numbers that cannot be represented with doubles and are loosing significant digits. And this really becomes an issue when your test suite use less significant digits to identify repeating patterns such as in cases 7 and 10. I was able to overcome this issue by using 14 digits, but some people used 16 (If someone else is having problems that's the way to go). Moreover, Andrew is right, a number like 0.333333 is technically not a repeating decimal.

Solution Comments

Solution 264188

1 Comment

1 Comment

Andrew Newell on 20 Jun 2013

If the number is a true repeater, then multiplying it by 999... for some number of 9's will result in an integer. The difficulty lies in the rounding. I had to tune the tolerance to deal with cases like .123451234512345, which aren't truly repeating.

Solution 131896

1 Comment

1 Comment

Khaled Hamed on 28 Aug 2012

Some cleaning up!

Problem Recent Solvers14

Problem Tags

decimal repeating string manipulation

Community Treasure Hunt

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

Start Hunting!

Problem 918. Find the repeating decimal pattern!

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers14

Suggested Problems

More from this Author6

Problem Tags

Community Treasure Hunt

Problem 918. Find the repeating decimal pattern!

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers14

Suggested Problems

More from this Author6

Problem Tags

Community Treasure Hunt

Players