sparsemat_main.cpp

斯坦福Energy211/CME211课《c++编程——地球科学科学家和工程师》的课件

// ENERGY211/CME211
//
// main.cpp - Main application file that tests functions from
// the SparseMatrix class
//

#include <iostream>
#include <cmath>

#include "sparsemat.h"

using namespace std;

int main() {
	
	try
	{
		// This creates a 3x3 zero matrix
		SparseMatrix A(3,3);
	
		A(1,1) = 1.0;
		cout << "(2,2) element:" << endl;
		double x = A(2,2);
		cout << "x = " << x << endl;
		// By trying to access the (2,2) element,
		// entries in the map are created even though
		// the element is zero
		cout << "A(2,2) = " << A(2,2) << endl;
		// So this will report nnz = 2 even though
		// it should be 1
		cout << "nnz = " << A.nnz() << endl;
		// This will correct the problem
		A.Squeeze();
		cout << "nnz = " << A.nnz() << endl;
		cout << endl;
		// Confirm that the matrix hasn't changed
		cout << "A:" << endl;
		cout << A;
	}
	catch(runtime_error e)
	{
		cout << e.what() << endl;
	}

	try
	{
		// Test basic matrix operations
		SparseMatrix A;
		A.Identity( 4 );
		A(0,1) = 2.0;
		A(1,2) = 3.0;
		A(2,3) = 4.0;
		cout << "A = \n";
		cout << A;
	
		SparseMatrix B = A * A;
		cout << "B = \n";
		cout << B;
		SparseMatrix T = B.Transpose();
		cout << "B^T = \n";
		cout << T;
		SparseMatrix C = B + T;
		cout << "C = \n";
		cout << C;
	}
	catch(runtime_error e)
	{
		cout << e.what() << endl;
	}

	return 0;
}