Problem 44950. Calculate Inner Product

Created by Pooja Lalan

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Given two input matrices, <tt>x</tt> and <tt>y</tt>, check if their inner dimensions match.<ul><li>If they match, create an output variable <tt>z</tt> which contains the product of <tt>x</tt> and <tt>y</tt></li><li>Otherwise, <tt>z</tt> should contain a custom string message</li></ul>Example:<pre class="language-matlab">x = [1 2;3 4]
y = [5;6]
</pre><tt>z = [17;39]</tt><pre class="language-matlab">x = [1 2 3;4 5 6]
y = [2 5;3 6]
</pre><tt>z = "Have you checked the inner dimensions?"</tt>OR<tt>z = "The inner dimensions are 3 and 2. Matrix multiplication is not possible"</tt>-------------------------------------------------------------------------------------------------------------------------------------------------------------NOTE - An example of combining numbers and strings together is shown below:<pre class="language-matlab">x = "The sum of " + 4 + " and " + 3 + " equals " + 7
</pre><pre class="language-matlab">x = 
</pre><pre> "The sum of 4 and 3 equals 7"</pre>

Solve

Solution Stats

12515 Solutions
4502 Solvers

Last Solution submitted on Jul 03, 2022

Last 200 Solutions

Problem Comments

9 Comments

9 Comments

Show 6 older comments

Rohiit Priyadarshan Muralidharan on 30 Mar 2020

I solved this question with an if condition and the size of my solution was 39. I found the size of the leading solution to be 14. This is the leading solution: function ans = in_prod(x,y)
"no";
try
x*y;
end
How is this even correct? I tried to paste the same solution instead of mine and the assertion failed. z is not mentioned anywhere in this code. Can someone enlighten me?

Pooja Lalan on 30 Mar 2020

If the output x*y is not assigned to any variable, MATLAB assigns it to the variable ans by default. In this solution, z has been replaced with ans in the function definition to return the unassigned output.

Hugo Ormo on 5 Apr 2020

I am confused... this ought to work:
function z = in_prod(x,y)
if size(x,2) == size(y,1)
z = x * y
else
z = "The inner dimensions are " + size(x) + " and " + size(y) + ". Matrix multiplication is not possible"
end

Adrià Fenollosa on 23 Jul 2020

This is dot product, not inner product, as the title suggests. They are not exactly the same.

Cheng Jin on 21 Oct 2020

I personally suggest substituting the title with 'dot product', as the description states.

Sebastian Duda on 27 Nov 2020

What is wrong with this code? It's working on the downloaded version.
[xrow,xcol]=size(x);
[yrow,ycol]=size(y);
if xcol==yrow
z = x*y
else
z='Have you checked the inner dimensions?'
end

霖陈 on 28 Oct 2021

please help me,what is wrong with this code?fail the third test...
function z = in_prod(x,y)
if size(x,2)==size(y,1);
z=x*y
else
z=''Have you checked the inner dimensions'
end
end

Isabella Stellitano on 14 Nov 2021

Thank you

Agam Sharma on 18 May 2022

x = [1 2;3 4]
y = [5;6]
[row1 column1] = size(x)
[row2 column2] = size(y)

if column1==row2
z=x*y %% I haven't used .* to avoid linear array performation
else
disp("the inner dimensions are mismatched")

end

Solution Comments

Solution 6970729

1 Comment

1 Comment

Haoran Tian on 26 Nov 2021

interesting

Solution 6931089

1 Comment

1 Comment

Josh Klueber on 21 Nov 2021

tricky

Solution 6514419

Solution 3916618

1 Comment

1 Comment

Frank Pang on 30 Nov 2020

this problem is a little tricky. you have to output the exactly string mentioned in the problem description, not a random string.

Solution 2882096

1 Comment

1 Comment

wenqi wang on 27 Aug 2020

function z = in_prod(x,y)
if length(x(1,:)) == length(y(:,1))
z = x*y;
else
z = "Have you checked the inner dimensions?"
end
end

Solution 2712270

1 Comment

1 Comment

Mrikwood on 19 Jul 2020

function z = in_prod(x,y)
if length(x(1,:))==length(y(:,1))
z=x*y;
else
z="Have you checked the inner dimensions?"
end
end

Solution 2626789

1 Comment

1 Comment

Umur Ulas Harman on 29 Jun 2020

function z = in_prod(x,y)
if size(x,2)==size(y,1)
z=x*y
else
z = "The inner dimensions are " + size(x,2) + " and " + size(y,1) + ". Matrix multiplication is not possible";
end
end

Solution 2581468

1 Comment

1 Comment

Piero Cimule on 19 Jun 2020

if size(x,2)==size(y,1)
z=x*y
else
z = "The inner dimensions are 3 and 2. Matrix multiplication is not possible"
end

Solution 2231713

1 Comment

1 Comment

Saad on 24 Apr 2020

Please, this code is working on Matlab but it did not work here , I think no problem with it
if size(x,2)==size(y,1)
z=x*y;
else
z = ['The inner dimensions are ', num2str(size(x,2)) ,' and ' ,num2str(size(y,1)), ' Matrix multiplication is not possible'];
end
display(z)

Solution 2231675

1 Comment

1 Comment

Saad on 24 Apr 2020

Please, this code is working on Matlab command widows, but in this problems it appears not correct, what is the problem please?

Solution 1946058

3 Comments

3 Comments

Jiahao CHANG on 1 Jul 2020

大佬强

Shuvo Kumar Paul on 29 Jul 2020

Very interesting and logical solution to the problem.

Haoyue Jiang on 12 Oct 2020

233，666

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Problem Tags

logic matrix manipulation

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Problem 44950. Calculate Inner Product

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Problem 44950. Calculate Inner Product

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