Problem 45282. Cryptography with A Square Matrix : Decoding

Created by Mehmet OZC

Solve Later

Previous Problem: Cryptography with A Square Matrix : Encoding
Now decode a double vector to a (hopefully!) meaningful text.
Inputs are encoded vector and key matrix.
   encodedVector = [1665 1624 1541 1549 1495 1501 486 510 534 1503 1552 1595 1192 747 836]
   key = magic(3);
inverse of key
   inverseKey = [0.147222222222222 -0.144444444444444 0.0638888888888889
               -0.0611111111111111 0.0222222222222222 0.105555555555556
               -0.0194444444444445 0.188888888888889 -0.102777777777778];
Reshape encodedVector so it has the same number of rows with key
   reshapedVector = [1665 1549 486 1503 1192;
                     1624 1495 510 1552 747;
                     1541 1501 534 1595 836];
Multiply inverseKey and reshapedVector, round it and reshape it;
 messageVector = [109 97 116 108 97 98 32 38 32 99 111 100 121 32 32];
char equivalent of message vector is 'matlab & cody'

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Last Solution submitted on Jun 15, 2025

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Christian Schröder on 28 Dec 2022

Your last two test cases do not actually test anything --- there's no assert() in these.

Dyuman Joshi on 28 Dec 2022

There are no answers defined by the author to test the last 2 cases.

Christian Schröder on 29 Dec 2022

@Duyman the missing correct answers are, respectively, 'backorder is an accumulation of customer orders that a manufacturer has promised for delviery at some future date.' and 'abc'.

Christian Schröder on 29 Dec 2022

(And yes, it really says 'delviery'; the original author probably had a typo in there he didn't catch.)

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Problem 45282. Cryptography with A Square Matrix : Decoding

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Problem 45282. Cryptography with A Square Matrix : Decoding

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