Problem 561. Find the jerk

Created by Kye Taylor

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>No, it's not the author of this problem...</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Jerk is the rate of change in acceleration over time of an object. So, if given the position of an object over time in the form of a 1-by-N vector, return the indices i where there is nonzero jerk.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Super rad bonus hint: The signal you need to find the jerk of will be given by the variable sig, created with the commands</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[h = 0.065; % stepsize\nt = -10:h:10;\nsigCoefs = 2*rand(1,3)-1;\nsig = polyval(sigCoefs,t);\nbreakPoint = randi(length(sig)-2)+1;\nsig(breakPoint) = (1.01)*sig(breakPoint); % this creates a nonzero jerk]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Check the signal visually with</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[plot(t,sig,'k.-')]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Now, using just sig, determine breakPoint.</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

152 Solutions
44 Solvers

Last Solution submitted on Jan 05, 2023

Last 200 Solutions

Problem Comments

4 Comments

4 Comments

Show 1 older comment

Kye Taylor on 7 Apr 2012

My apologies to the second solver of the problem... The test-suite changed so that the signal sig is no longer simply t^2. With that type of hint, someone could just difference the perturbed signal with t^2 to find the jerk.. Or someone could simply look for the point where the acceleration is negative... That's not my intent. I want a nonzero jerk. Now sig is somewhat random.

Venu Lolla on 8 Apr 2012

Kye, not a problem. I will try again. Cheers.

Kye Taylor on 8 Apr 2012

I realize that an even better signal would be one created as before except with the modification

sig(breakPoint) = (-1)^(randi(2)-1)*(1.01)*sig(breakPoint);

so that the jerk could be positive or negative...

Richard Zapor on 15 Dec 2012

Many of the solutions return multiple invalid answers. The test condition "any" allows these to pass. Suggest change "any" to "all". all(abs(findAJerk(sig) - breakPoint)<=6)

Problem Recent Solvers44

Problem Tags

Community Treasure Hunt

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

Start Hunting!

Problem 561. Find the jerk

Solution Stats

Last 200 Solutions

Problem Comments

Problem Recent Solvers44

Suggested Problems

More from this Author1

Problem Tags

Community Treasure Hunt

Problem 561. Find the jerk

Solution Stats

Last 200 Solutions

Problem Comments

Problem Recent Solvers44

Suggested Problems

More from this Author1

Problem Tags

Community Treasure Hunt

Players