utils.cpp File Reference

Implementation of utility functions for matrix operations. More...

#include "utils.h"
#include <iostream>
#include <fstream>
#include <sstream>
#include <cmath>
#include <iomanip>

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Functions
bool	InitMatrix (vector< vector< double > > &m, const string &filename, int &rows, int &cols)
	Initializes the matrix by reading from a .in file.
void	ShowEquations (const vector< vector< double > > &m, int rows, int cols)
	Displays the system of linear equations.
bool	CheckConsistency (const vector< vector< double > > &m, int rows, int cols)
	Checks the consistency of the system of equations.
void	DisplaySolution (const vector< double > &solution)
	Displays the unique solution.
chrono::steady_clock::time_point	StartTimer ()
void	StopTimer (const chrono::steady_clock::time_point &start)

Detailed Description

Implementation of utility functions for matrix operations.

This file contains the implementations of functions that handle reading matrices from .in files and displaying the corresponding system of linear equations. These utility functions are essential for the initialization and output of matrix data used in solving linear systems.

Definition in file utils.cpp.

Function Documentation

CheckConsistency()

bool CheckConsistency	(	const vector< vector< double > > &	m,
		int	rows,
		int	cols )

Checks the consistency of the system of equations.

Parameters

m	The matrix representing the system.
rows	Number of rows in the matrix.
cols	Number of columns in the matrix.

Returns

true If the system is consistent.

false If the system is inconsistent.

Definition at line 123 of file utils.cpp.

{
    for (int i = 0; i < rows; i++)
    {
        bool all_zero = true;
        for (int j = 0; j < cols - 1; j++)
        {
            if (fabs(m[i][j]) > 1e-12)
            {
                all_zero = false;
                break;
            }
        }
        if (all_zero && fabs(m[i][cols - 1]) > 1e-12)
        {
            return false;
        }
    }
    return true;
}

DisplaySolution()

void DisplaySolution

(

const vector< double > &

solution

)

Displays the unique solution.

Parameters

solution

The solution vector.

Definition at line 147 of file utils.cpp.

{
    cout << "The system has a unique solution:" << endl;
    for (size_t i = 0; i < solution.size(); i++)
    {
        cout << "x" << i + 1 << " = " << fixed << setprecision(4) << solution[i] << endl;
    }
}

InitMatrix()

bool InitMatrix	(	vector< vector< double > > &	m,
		const string &	filename,
		int &	rows,
		int &	cols )

Initializes the matrix by reading from a .in file.

Parameters

m	Reference to the matrix to be initialized.
filename	Name of the input file.
rows	Reference to store the number of rows.
cols	Reference to store the number of columns.

Returns

true If the matrix was successfully initialized.

false If there was an error during initialization.

Definition at line 24 of file utils.cpp.

{
    ifstream in(filename);
    if (!in.is_open())
    {
        cerr << "Error: Cannot open file " << filename << endl;
        return false;
    }
 
    // Read the matrix dimensions dynamically
    string line;
    rows = 0;
    cols = 0;
    vector<vector<double>> temp_matrix;
    while (getline(in, line))
    {
        if (line.empty())
            continue; // Skip empty lines
        vector<double> row;
        double num;
        istringstream iss(line);
        while (iss >> num)
        {
            row.push_back(num);
        }
        if (cols == 0)
        {
            cols = row.size();
        }
        else if (static_cast<int>(row.size()) != cols)
        {
            cerr << "Error: Inconsistent number of columns in the file." << endl;
            in.close();
            return false;
        }
        temp_matrix.push_back(row);
        rows++;
    }
    in.close();
 
    if (rows == 0 || cols < 2)
    {
        cerr << "Error: The matrix must have at least one equation and one variable." << endl;
        return false;
    }
 
    // Assign to m
    m = temp_matrix;
    return true;
}

ShowEquations()

void ShowEquations	(	const vector< vector< double > > &	m,
		int	rows,
		int	cols )

Displays the system of linear equations.

Parameters

m	The matrix representing the system.
rows	Number of equations.
cols	Number of variables plus one (for constants).

Definition at line 78 of file utils.cpp.

{
    cout << "The current system of linear equations is:" << endl;
 
    for (int i = 0; i < rows; i++)
    {
        string equation = "";
        for (int j = 0; j < cols - 1; j++)
        {
            // Check if the coefficient is an integer
            double coeff = round(m[i][j] * 1e12) / 1e12; // Handle floating-point precision
 
            if (fabs(coeff - round(coeff)) < 1e-12)
            {
                equation += to_string(static_cast<long long>(round(coeff))) + " x" + to_string(j + 1);
            }
            else
            {
                // Set precision for floating-point numbers
                equation += to_string(round(m[i][j] * 10000) / 10000.0) + " x" + to_string(j + 1);
            }
 
            if (j < cols - 2)
                equation += " + "; // Add space around '+' for better readability
        }
 
        // Handle constant term
        double const_term = round(m[i][cols - 1] * 1e12) / 1e12;
        if (fabs(const_term - round(const_term)) < 1e-12)
        {
            equation += " = " + to_string(static_cast<long long>(round(const_term)));
        }
        else
        {
            equation += " = " + to_string(round(m[i][cols - 1] * 10000) / 10000.0);
        }
 
        cout << equation << endl; // Output the equation
    }
    cout << endl; // Add a blank line at the end
}

StartTimer()

chrono::steady_clock::time_point StartTimer

(

)

Definition at line 157 of file utils.cpp.

{
    return chrono::steady_clock::now();
}

StopTimer()

void StopTimer

(

const chrono::steady_clock::time_point &

start

)

Definition at line 162 of file utils.cpp.

{
    auto end = chrono::steady_clock::now();
    chrono::duration<double> elapsed = end - start;
    cout << "Time elapsed: " << elapsed.count() << " seconds." << endl;
}