2.2.3.9.42 matrixbase::GetUpperTriangular

GetUpperTriangular

1 Description
2 Syntax
3 Parameters
4 Return
5 Examples
6 Remark
7 See Also
8 Header to Include

Description

Get an upper triangular matrix from this matrix.

Syntax

int GetUpperTriangular( matrixbase & mbResult, int nNthDiagonal = 0 )

Parameters

mbResult: [output] The result matrix containing only the lower part
nNthDiagonal: [input] The number specifying N-th diagonal, default 0 is the main diagonal, > 0 is above the main diagonal, and < 0 is below the main diagonal.

Return

Returns 0 on success and a non-zero error code on failure.

-1=Internal cast error.

Examples

EX1

void matrixbase_GetUpperTriangular_ex1()
{
    matrix<double> mat1 = {
        { 1, 1, 99,  1,  1},
        {99, 1,  1,  1,  1},
        { 1, 1,  1,  1,  1}
    };
    mat1[1][0]=NANUM;  // set row=2,col=1 to NANUM
    mat1[0][2]=NANUM;  // set row=1,col=3 to NANUM
    matrix<double> mat2;
    
	int rc = mat1.GetUpperTriangular(mat2); 
    if(rc!=0) 
        printf(" Error: GetUpperTriangular failed. Error Code=%d\n",rc);
    else{
    	printf("The matrix is:\n");
        for(int ii=0; ii< mat2.GetNumRows(); ii++){
			for(int jj=0; jj< mat2.GetNumCols(); jj++) 
				printf("%g  ", mat2[ii][jj]);
			printf("\r\n");
        }
    }
}

EX2

// Convert a matrix to the upper triangular matrix
void matrixbase_GetUpperTriangular_ex2()
{ 
    matrix<double> mat1 = {
        { 1, 1, 99,  1,  1},
        {99, 1,  1,  1,  1},
        { 1, 1,  1,  1,  1}
    };
    mat1[1][0]=NANUM;  // set row=2,col=1 to NANUM
    mat1[0][2]=NANUM;  // set row=1,col=3 to NANUM
 
//   Input matrix is:
//        { 1, 1, --,  1,  1}
//        {--, 1,  1,  1,  1}
//        { 1, 1,  1,  1,  1}
 
//   UpperTriangular matrix is:
//        { 1, 1, --,  1,  1}
//        { 0, 1,  1,  1,  1}
//        { 0, 0,  1,  1,  1}

//   UpperTriangular matrix from 1th diagonal above the main diagonal is:
//        { 0, 1, --,  1,  1}
//        { 0, 0,  1,  1,  1}
//        { 0, 0,  0,  1,  1}
 
    MatrixPage MatPg1;
    MatPg1.Create("Origin");
    MatrixLayer MatLy1 = MatPg1.Layers(0);
    Matrix Mat1(MatLy1);
    Mat1 = mat1;
    printf("  Original matrix is %s.\n",Mat1.GetName());
 
    MatrixPage MatPg2;
    MatPg2.Create("Origin");
    MatrixLayer MatLy2 = MatPg2.Layers(0);
    Matrix Mat2(MatLy2);

    //Put the upper triangular matrix of Mat1 to Mat2 
    int rc=Mat1.GetUpperTriangular(Mat2); 
    if(rc!=0) 
        printf("  Error: GetUpperTriangular failed. Error Code=%d\n",rc);
    else {
        printf("  Upper triangular matrix is %s.\n",Mat2.GetName());
        printf("  Note that the NANUM in the upper triangular area is preserved,\n");
        printf("  Note that the NANUM in the lower triangular area became 0,\n");
    }
    
    MatrixPage MatPg3;
    MatPg3.Create("Origin");
    MatrixLayer MatLy3 = MatPg3.Layers(0);
    Matrix Mat3(MatLy3);
    
    //Put the upper triangular matrix of Mat1 from 1th diagonal above the main diagonal to Mat3
    rc=Mat1.GetUpperTriangular(Mat3,1);  
    if(rc!=0) 
        printf("  Error: GetUpperTriangular failed. Error Code=%d\n",rc);
    else {
        printf("  Upper triangular matrix is %s.\n",Mat3.GetName());
        printf("  Note that the NANUM in the upper triangular area is preserved,\n");
        printf("  Note that the NANUM in the lower triangular area became 0,\n");
    }
}