• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 251
  • Last Modified:

C++ Help Multiplying Matrices

Hello I would like help in multiplying 2 matrices in the attached code,  the 2 matrices being multiplied are the V_prime_matrix[6][1] and the d_prime_matrix[1][6] and the result matrix being f_bar would be a single number.

Can anyone help me?
QAP-EE-Code.txt
0
college_student
Asked:
college_student
  • 6
  • 6
1 Solution
 
jkrCommented:
>> result matrix being f_bar would be a single number.

That is right, in your special case the result of 'V_prime_matrix[6][1] * d_prime_matrix[1][6]' es quivalent to the scalar product (http://en.wikipedia.org/wiki/Scalar_product) - so you can rewrite your code to just one loop:

int f_bar = 0;
				for (int i = 0; i < 6; i++)
				{
					f_bar += V_prime_matrix[x][0] * d_prime_matrix[0][i];
					cout << f_bar << endl;
				}

Open in new window

0
 
jkrCommented:
Ooops, that formatting is downright ugly, make that

int f_bar = 0;

	for (int i = 0; i < 6; i++)
	{
		f_bar += V_prime_matrix[x][0] * d_prime_matrix[0][i];
		cout << f_bar << endl;
	}
            

Open in new window

0
 
college_studentAuthor Commented:
thanks, but this didnt work. Im getting errors
0
Cloud Class® Course: Microsoft Office 2010

This course will introduce you to the interfaces and features of Microsoft Office 2010 Word, Excel, PowerPoint, Outlook, and Access. You will learn about the features that are shared between all products in the Office suite, as well as the new features that are product specific.

 
jkrCommented:
Um, what errors exactly?
0
 
college_studentAuthor Commented:
why did you change it to [x][0] and [0][1]? I dont understand that.
Also shouldnt it be f_bar[x][x] or something similar, not just f_bar by itself?
0
 
college_studentAuthor Commented:
Errors:

Error      1      error C2106: '+=' : left operand must be l-value      c:\users\carlosneal\documents\visual studio 2013\projects\consoleapplication4\consoleapplication4\source.cpp      52      1      ConsoleApplication4
      2      IntelliSense: expression must be a modifiable lvalue      c:\Users\carlosneal\Documents\Visual Studio 2013\Projects\ConsoleApplication4\ConsoleApplication4\Source.cpp      52      3      ConsoleApplication4
0
 
jkrCommented:
Ah, I see - sorry, but then make that

f_bar[0][0] = 0;

	for (int i = 0; i < 6; i++)
	{
		f_bar[0][0] += V_prime_matrix[x][0] * d_prime_matrix[0][i];
		
	}

        cout << f_bar[0][0] << endl;
            
                                            

Open in new window

0
 
college_studentAuthor Commented:
still getting errors, its saying that i and j are unreferenced local variables and x is unititialized local variable
0
 
jkrCommented:
Copy and paste error, sorry again - the snippet should be

f_bar[0][0] = 0;

	for (int i = 0; i < 6; i++)
	{
		f_bar[0][0] += V_prime_matrix[i][0] * d_prime_matrix[0][i];
		
	}

        cout << f_bar[0][0] << endl;
                                    

Open in new window


And you should of course remove the declarations of the variables you aren't using any longer, if not, you get these warnings - so that is

int main()
{
	display_opening_logo();
	cout << setw(16) << SKIP << endl;
	
	costMatrix();
	int cost_of_original_layout = f_star();
	cout << "Press <Enter> to coninue " << endl;
	cout << setw(16) << SKIP << endl;
	char ch = _getch();
	cout << "The cost of the original existing layout is " << "$" << cost_of_original_layout << endl;

	
	for (int i = 0; i < 6; i++)
	{
		f_bar[0][0] += V_prime_matrix[i][0] * d_prime_matrix[0][i];		
	}

        cout << f_bar[0][0] << endl;

	system("PAUSE");
	return 0;

}

Open in new window

0
 
college_studentAuthor Commented:
Thanks it works now!!
0
 
college_studentAuthor Commented:
Very helpful and resourceful!!
0
 
jkrCommented:
You're most welcome ;o)
0
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

Featured Post

Free Tool: ZipGrep

ZipGrep is a utility that can list and search zip (.war, .ear, .jar, etc) archives for text patterns, without the need to extract the archive's contents.

One of a set of tools we're offering as a way to say thank you for being a part of the community.

  • 6
  • 6
Tackle projects and never again get stuck behind a technical roadblock.
Join Now