Problem 44352. The Top 5 Primes

Created by Peng Liu

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>This problem series invites you to solve two simple problems related to the integer NUMBER FIVE, in order to celebrate</w:t></w:r><w:r><w:t> </w:t></w:r><w:hyperlink w:docLocation=\"https://www.mathworks.com/matlabcentral/cody/contests/1?s_tid=Cody5YA_cody_home\"><w:r><w:t>Cody's 5th birthday</w:t></w:r></w:hyperlink><w:r><w:t>.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>In this problem, let's find the top 5 greatest prime numbers along the first non-singleton dimension of an input array.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Example</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"ListParagraph\"/><w:numPr><w:numId w:val=\"1\"/></w:numPr></w:pPr><w:r><w:t>If the input is a vector, the output is a length-5 vector containing the top 5 prime numbers of the input sorted in descending order. Append NaNs as needed in the output if the number of primes is less than 5.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[x = 1:10;\ny = [7 5 3 2 NaN];]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"ListParagraph\"/><w:numPr><w:numId w:val=\"1\"/></w:numPr></w:pPr><w:r><w:t>If the input is a m-by-n (m &gt;= 5) matrix, the output is a 5-by-n matrix containing the column-wise top 5 prime numbers of the input matrix sorted in descending order. Whenever there are less than 5 primes found in a specific column of the input, simply append NaNs as needed in the same column of the output.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[% Input x is a matrix\nx = [17 6 3\n 13 8 17\n 1 2 5\n 5 3 7\n 7 11 2\n 31 7 6];\n\n% Output y\ny = [31 11 17\n 17 7 7\n 13 3 5\n 7 2 3\n 5 NaN 2];]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Previous problem in this series:</w:t></w:r><w:r><w:t> </w:t></w:r><w:hyperlink w:docLocation=\"https://www.mathworks.com/matlabcentral/cody/problems/44342-spot-the-first-occurrence-of-5\"><w:r><w:t>Spot the First Occurrence of 5</w:t></w:r></w:hyperlink></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>"}]}

This problem series invites you to solve two simple problems related to the integer NUMBER FIVE, in order to celebrate <a href = "https://www.mathworks.com/matlabcentral/cody/contests/1?s_tid=Cody5YA_cody_home">Cody's 5th birthday</a>.In this problem, let's find the top 5 greatest prime numbers along the first non-singleton dimension of an input array.Example<ul><li>If the input is a vector, the output is a length-5 vector containing the top 5 prime numbers of the input sorted in descending order. Append NaNs as needed in the output if the number of primes is less than 5.</li></ul><pre class="language-matlab">x = 1:10;
y = [7 5 3 2 NaN];
</pre><ul><li>If the input is a m-by-n (m &gt;= 5) matrix, the output is a 5-by-n matrix containing the column-wise top 5 prime numbers of the input matrix sorted in descending order. Whenever there are less than 5 primes found in a specific column of the input, simply append NaNs as needed in the same column of the output.</li></ul><pre class="language-matlab">% Input x is a matrix
x = [17 6 3
 13 8 17
 1 2 5
 5 3 7
 7 11 2
 31 7 6];
</pre><pre class="language-matlab">% Output y
y = [31 11 17
 17 7 7
 13 3 5
 7 2 3
 5 NaN 2];
</pre>Previous problem in this series: <a href = "https://www.mathworks.com/matlabcentral/cody/problems/44342-spot-the-first-occurrence-of-5">Spot the First Occurrence of 5</a>

This problem series invites you to solve two simple problems related to the integer NUMBER FIVE, in order to celebrate <https://www.mathworks.com/matlabcentral/cody/contests/1?s_tid=Cody5YA_cody_home Cody's 5th birthday>.

In this problem, let's find the top 5 greatest prime numbers along the first non-singleton dimension of an input array.

Example

* If the input is a vector, the output is a length-5 vector containing the top 5 prime numbers of the input sorted in descending order. Append NaNs as needed in the output if the number of primes is less than 5.

x = 1:10;
  y = [7 5 3 2 NaN];

* If the input is a m-by-n (m >= 5) matrix, the output is a 5-by-n matrix containing the column-wise top 5 prime numbers of the input matrix sorted in descending order. Whenever there are less than 5 primes found in a specific column of the input, simply append NaNs as needed in the same column of the output.

% Input x is a matrix
  x = [17     6     3
       13     8    17
        1     2     5
        5     3     7
        7    11     2
       31     7     6];

% Output y
  y = [31    11    17
       17     7     7
       13     3     5
        7     2     3
        5   NaN     2];

Previous problem in this series: <https://www.mathworks.com/matlabcentral/cody/problems/44342-spot-the-first-occurrence-of-5 Spot the First Occurrence of 5>

Solve

Solution Stats

1174 Solutions
277 Solvers

Last Solution submitted on Sep 27, 2021

Last 200 Solutions

Problem Comments

Solution Comments

Solution 1937216

1 Comment

1 Comment

jljl jacky on 19 May 2021

funny?i don't think so

Solution 1308605

1 Comment

1 Comment

jljl jacky on 19 May 2021

wonderful,don't know maxk function

Problem Recent Solvers277

Problem Tags

cody5

Community Treasure Hunt

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

Start Hunting!