Problem 45268. Restricted Multiplication v1

Created by Jonathan

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This problem is Restricted Addition v4 with multiplication and more restrictions.
multiply two inputs without use of common arithmetic operations. Inputs can be matrices as well. Unfortunately, in order to enforce this restriction, other restrictions are imposed. For example, use of 'e' is restricted to prevent use of 'eval' functions.
Until the Cody test system is changed, the hack below will work (as it currently does on every Cody problem). However, this type of solution is not appreciated.
function ans = fileread(~), ''
Other hacks are appreciated. If you can circumvent the restrictions (with your code running when called by tests 2, 3, ...) to use multiplication, then you have a valid and welcomed solution.
This version of the problem does not require hacks at all, just some basic MATLAB creativity!
See also:
Restricted Addition v1, Restricted Addition v2, Restricted Addition v3, Restricted Addition v4
Restricted Subtraction v1
Restricted Multiplication v1

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Last Solution submitted on Apr 30, 2024

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埃博拉酱 on 6 Nov 2020

Limit on single letter f and e is ridiculous. for loop and select case and even end it inhibited. English is full of es.

埃博拉酱 on 6 Nov 2020

To hack fileread is the only way to break in I promise.

Rafael S.T. Vieira on 7 Nov 2020

I've spent a lot of time to solve all problems of this series, and overall it is a good series with the sole exception of these last two problems that need some fixing. I recommend that you, an author, first try to solve your problems before posting them at Cody. Please, don't just imagine that there is a solution.
Cody is not a research platform, and as such, all problems must have a solution. I am almost sure that no one is aware of all restricted functions when we prohibit the letters a, e, and f (it is not just eval, accumarray, and file or figure handling). Please, try to improve these restrictions by stating clearly all functions that are prohibited.

Rafael S.T. Vieira on 7 Nov 2020

This problem's title is kind of misleading. Multiplication of matrices is not a multiplication of numbers (scalars) but a dot product of vectors. The test suite mixes the two operations, yet they are not the same. Moreover, we cannot use an if struct (because of the f-letter prohibition). I agree with 埃博拉酱; there is very likely no way to solve this problem without a hack (whatever function we use probably won't have the two necessary behaviors).

goc3 on 9 Nov 2020

The tests involving single letters (a, e, f) have been updated to two or three letters to potentially allow for non-hacking solutions. Also, returned values are now tested against a tolerance.

Jean-Marie Sainthillier on 15 Jul 2022

Too many restrictions and all solutions submitted are the same.
As in life...

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Problem 45268. Restricted Multiplication v1

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Problem 45268. Restricted Multiplication v1

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