Cody

# Problem 45279. Cryptography with A Square Matrix : Encoding

Matrix inverse operation can be used to encode or decode of a message. For example

`    text = 'matlab & cody'. `

numeric equivalent is

`    num = [109 97 116 108 97 98 32 38 32 99 111 100 121]`

let

`   key = magic(3);`

key is an arbitrary square matrix and its inverse is exist.

reshape the vector num so it has the same number of rows with key matrix

```   numMatrix = [109 108 32 99 121;
97 97 38 111 32;
116 98 32 100 32];```

Note that last two elements are filled with 32 which is the numeric equivalent of blank character ' '.

Finally multiply key with numMatrix (and reshape it) to obtain an encoded vector.

`   encodedVector= [1665 1624 1541 1549 1495 1501 486 510 534 1503 1552 1595 1192 747 836]`

if you multiply inverse of key with reshaped encodedVector you can obtain the ascii numbers of secret message.

Next Problem : Cryptography with A Square Matrix : Decoding

Inspired from:

Barnett, R.A., Ziegler, M.R. and Byleen, K.E. (2015). Finite Mathematics for Business, Economics, Life Sciences, and Social Sciences. Pearson, 13th (Global) Edition. p:245-247.

### Solution Stats

83.33% Correct | 16.67% Incorrect
Last Solution submitted on Feb 09, 2020