Problem 1972. Convert matrix to 3D array of triangular matrices

Created by Matthew Eicholtz

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>Given a 2D numeric array x in which each column represents the vectorized form of an upper triangular matrix, return a 3D array y containing the concatenated triangular matrices.</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 size of the input matrix x is MxN, then the size of the output matrix y is PxPxN, where M = sum(1:P)</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>You may assume that P&lt;=100</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:rPr><w:b/></w:rPr><w:t>Example</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>If</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[x = 1  7 13\n    2  8 14\n    3  9 15\n    4 10 16\n    5 11 17\n    6 12 18]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>then</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[y(:,:,1) =  1  2  4\n            0  3  5\n            0  0  6\n\ny(:,:,2) =  7  8 10\n            0  9 11\n            0  0 12\n\ny(:,:,3) = 13 14 16\n            0 15 17\n            0  0 18]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:rPr><w:i/></w:rPr><w:t>NOTE:</w:t></w:r><w:r><w:t> If you are wondering why this seems like a strange task, it is inspired by a genotype-&gt;phenotype mapping I am doing in a genetic algorithm.</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

172 Solutions
59 Solvers

Last Solution submitted on Mar 17, 2021

Last 200 Solutions

Problem Comments

Solution Comments

Solution 4613965

1 Comment

1 Comment

Lincoln Poon on 18 Jan 2021

I keep failing the 'assert(isequal(x,xb))' part of the last test.
Can someone please give me some ideas on how to fix it?

Problem Recent Solvers59

Problem Tags

Community Treasure Hunt

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

Start Hunting!

Problem 1972. Convert matrix to 3D array of triangular matrices

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers59

Suggested Problems

More from this Author44

Problem Tags

Community Treasure Hunt

Problem 1972. Convert matrix to 3D array of triangular matrices

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers59

Suggested Problems

More from this Author44

Problem Tags

Community Treasure Hunt

Players