c++ matrix operation

molatelo · #1 10-May-2007, 04:27

Hi!

I'm building a Class for matrixes.

I have already built several funtions for adding, subtracting, transpose, multiply,..

Now I'm trying to do a functions to calculate the dot and cross products as well as calculating the transpose and the inverse of a matrix. And also the methods to traverse the matrix row by row as well as column by column.

Can anyone help me?

CPP / C++ / C Code:

class CMatrix  
{
public:
	void Identity();
	void SetMaxColRow(int nRow, int nCol);
	void SetElement(int nRow, int nCol, double element);
	void Show();

	double GetElement(int nRow, int nCol);

	CMatrix operator+(CMatrix tmpMatriz);
	CMatrix operator-(CMatrix tmpMatriz);
	CMatrix operator*(double scalar);
	CMatrix operator*(CMatrix tmpMatriz);
	CMatrix Transpose();
	CMatrix(int nRows, int nCols);
	CMatrix();
	
	virtual ~CMatrix();
	
	int m_nRows;
	int m_nCols;
	

private:
	double **m_pMatriz;





// constructor
CMatrix::CMatrix(int nRows, int nCols)
{
	m_nCols= nCols;
	m_nRows = nRows;

	m_pMatriz = new double* [m_nRows];
	for (int i=0; i<m_nRows; i++)
	{
		m_pMatriz[i] = new double[m_nCols];
		for (int j=0; j<m_nCols; j++)
			m_pMatriz[i][j] = 1.0;
	}
}

davekw7x · #2 10-May-2007, 08:10

Quote:

Originally Posted by molatelo

I have already built several funtions for adding, subtracting, transpose, multiply,..

Now I'm trying to do a functions to calculate the dot and cross products as well as calculating the transpose and the inverse of a matrix. And also the methods to traverse the matrix row by row as well as column by column.

For dot, cross, transpose, just use the definitions. All of them are at least as "easy" as matrix multiplication. If you try to apply one of these definitions but get stuck then:

1. Post the code that you tried, including a main() function that tests the operation in question.
2. Post the input that you gave the function for testing
3. Show the output that the program.
4. Tell us what you don't understand about the difference between 2 and 3.

If by "traversing" you mean printing out the values of the elements, then just make two loops:
If you want to print out row by row:
The outer loop index ranges from 0 to the number of rows and the inner loop ranges from 0 to the number of columns. Print out the matrix value for each step of the inner loop.

For the inverse: well, that's a little more involved. One of the more popular and effective methods is called Gauss Jordan. Look it up.

Regards,

Dave

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c++ matrix operation

Re: c++ matrix operation