Problem 876. Sum the entries of each column of a matrix which satisfy a logical condition.

Created by Ken Deeley

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>Given a numeric matrix A and a logical array L of the same size as A, return a row vector S containing the columnwise sums of the entries of A which satisfy L (i.e. where there is a true value in the logical array L). If L contains a column of false values, then the corresponding entry of S should be zero.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/><w:jc w:val=\"left\"/></w:pPr><w:r><w:t>Examples:</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/><w:jc w:val=\"left\"/></w:pPr><w:r><w:t>1) If A = [1, 2; 3, 4] and L = [true false; false true], then S should be the row vector [1 4].</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/><w:jc w:val=\"left\"/></w:pPr><w:r><w:t>2) If A = triu(ones(3)) and L = logical(A), then S should be the row vector [1 2 3].</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/><w:jc w:val=\"left\"/></w:pPr><w:r><w:t>3) If A = repmat(1:3, 3, 1) and L = [false(3,1), true(3, 2)], then S should be the row vector [0 6 9].</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

370 Solutions
136 Solvers

Last Solution submitted on Jan 18, 2021

Last 200 Solutions

Problem Comments

Problem Recent Solvers136

Problem Tags

matrix manipulation

Community Treasure Hunt

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

Start Hunting!

Problem 876. Sum the entries of each column of a matrix which satisfy a logical condition.

Solution Stats

Last 200 Solutions

Problem Comments

Problem Recent Solvers136

Suggested Problems

More from this Author4

Problem Tags

Community Treasure Hunt

Problem 876. Sum the entries of each column of a matrix which satisfy a logical condition.

Solution Stats

Last 200 Solutions

Problem Comments

Problem Recent Solvers136

Suggested Problems

More from this Author4

Problem Tags

Community Treasure Hunt

Players