Problem 44381. Cache me Outside

Created by @bmtran (Bryant Tran)

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{"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>The test suite includes a simple recursive Fibonacci sequence generator, but it's terribly inefficient. One simple method for improving its performance is using a technique called memoization. Write a function that takes a function_handle that we wish to memoize and returns a function_handle to a memoized version of the initial handle.</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>"}]}

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Last Solution submitted on Apr 14, 2023

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@bmtran (Bryant Tran) on 17 Oct 2017

Whoops, accidentally had the answer in the test suite. Fixed now.

Paul Dostert on 20 Oct 2017

Bryant,

Any chance you can elaborate a bit? I can make a memoized fibonacci code, but that's not really what you're asking. I don't get what the function call with 2 arguments (and 2nd argument the function itself) is in the test set: seq = memfib(n-1, memfib);

Sorry for the confusion.

James on 2 Nov 2017

Paul, it uses a feature that was just introduced in R2017a. If the answer hadn't accidentally been in the test suite, I never would have figured this one out either!

Andrew Newell on 7 Dec 2017

I tried comparing this code with a non-memoized version, and it was 6 times slower!

Hans Kramer on 25 Apr 2018

Love the name of the problem.^^

Dyuman Joshi on 16 Sep 2021

As difficult as the problem looks, (one of the) solution is quite easy and straight forward.

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