Problem 813. Multiply 2 numbers

Created by Aurelien Queffurust

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Very easy, you just have to multiply 2 numbers but you cannot use the following signs (*, /, - ,^) ,mtimes , times, cross, prod, cumprod , dec2bin, int2str and num2str functions. Will you take up the challenge?!

Example : x= 3; y= 2;

output = 6 since 3*2 = 6 :)

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1868 Solutions
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Last Solution submitted on Apr 02, 2020

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Aurelien Queffurust on 9 Jul 2012

As Richard made me notice by email, tests 5 and 6 (using randi and non-integer) were not enable. As I have rescored all solutions, some previous solutions which passed the test, do not pass it anymore.

James on 9 Jul 2012

Can you please set a tolerance for the submitted answers? Using exp(log(x)+log(y)) fails nearly all possibilities for test case 5, with the biggest error being roughly 2.5e-11.

Ilias Patelakis on 24 Oct 2017

Nice one. It would be more challenging to add a test case where both function arguments are decimal numbers. :)

Jiahang Li on 4 Feb 2018

You can try adding, and something wonderful happens.

Solution Comments

Solution 1445729

1 Comment

1 Comment

md.wahid tousif_rahman on 21 Feb 2018

Most foul one

Solution 1433565

1 Comment

1 Comment

Jiahang Li on 4 Feb 2018

funny~

Solution 1117273

1 Comment

1 Comment

Jess Stuart on 8 Feb 2017

exp(log(x)+log(y)) works with a trivial amount of roundoff error. Matlab is a numeric language. Using Isequal() is dumb.

Solution 415606

2 Comments

2 Comments

Dimitrios on 8 Mar 2014

i cant understand why test 1 fails :/

Aurelien Queffurust on 10 Mar 2014

It fails because you use the minus sign and there is the following test :
assert(isempty(strfind(filetext, '-')))

Solution 362049

2 Comments

2 Comments

Ramoflaple on 11 Aug 2015

good use of 'linspace'

David Verrelli on 10 Nov 2017

What if _both_ x _and_ y were either negative or non-integers though?

Solution 250534

2 Comments

2 Comments

Kumar on 29 May 2013

Test 1 is always showing Fail. This is disgusting. May be some error on the creator part. Kindly check...

Ned Gulley on 29 May 2013

The error for Test 1 says "Output argument 'output' (and maybe others) not assigned". Close examination of your code reveals that when x is 1 and y is 2, you go down the first switch of the outer "if" statement, and sure enough, output never gets assigned and the function fails.

Solution 106284

1 Comment

1 Comment

David Young on 4 Jul 2012

Only works for scalars of course.

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Problem 813. Multiply 2 numbers

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Problem 813. Multiply 2 numbers

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