# Класс Polynomial

1 часть задания
unknown
csharp
7 months ago
5.7 kB
3
Indexable
Never
```using System;

namespace WindowsFormsApp1
{
using System.Text;

public class Polynomial
{

public double[] Coefficients => (double[])_coefficients.Clone();
public int Degree => _coefficients.Length - 1;

public Polynomial(double[] c)
{
var n = c.Length;
if (n == 0)
throw new ArgumentException("Пустой массив коэффициентов полиномов");
while (n > 1 && c[n - 1] == 0.0)
--n;

var ctx = new double[n];
Array.Copy(c, 0, ctx, 0, n);
_coefficients = ctx;
}

public double Evaluate(double x)
{
var n = Degree;
var result = _coefficients[n];

for (var j = n - 1; j >= 0; --j)
result = x * result + _coefficients[j];

return result;
}

public static Polynomial operator +(Polynomial u, Polynomial p)
{
var lowLength = Math.Min(u._coefficients.Length, p._coefficients.Length);
var highLength = Math.Max(u._coefficients.Length, p._coefficients.Length);
var newCoefficients = new double[highLength];

for (var i = 0; i < lowLength; ++i)
{
newCoefficients[i] = u._coefficients[i] + p._coefficients[i];
}

var src = u._coefficients.Length < p._coefficients.Length
? p._coefficients
: u._coefficients;
Array.Copy(src, lowLength,
newCoefficients,
lowLength,
highLength - lowLength);
return new Polynomial(newCoefficients);
}

public static Polynomial operator -(Polynomial u, Polynomial p)
{
var lowLength = Math.Min(u._coefficients.Length, p._coefficients.Length);
var highLength = Math.Max(u._coefficients.Length, p._coefficients.Length);
var newCoefficients = new double[highLength];

int i;
for (i = 0; i < lowLength; ++i)
newCoefficients[i] = u._coefficients[i] - p._coefficients[i];
if (u._coefficients.Length < p._coefficients.Length)
{
for (i = lowLength; i < highLength; ++i)
newCoefficients[i] = -p._coefficients[i];
}
else
{
Array.Copy(u._coefficients, lowLength,
newCoefficients,
lowLength, highLength - lowLength);
}

return new Polynomial(newCoefficients);
}

public static Polynomial operator --(Polynomial p)
{
var n = p.Degree;
// Проверяем, является ли полином уже многочленом нулевой степени
if (n == 0)
return new Polynomial(new[] { 0.0 });
var newCoefficients = new double[n];
Array.Copy(p._coefficients, 0,
newCoefficients, 0, n);
return new Polynomial(newCoefficients);
}

public static Polynomial operator *(Polynomial u, Polynomial p)
{
var newCoefficients = new double[u._coefficients.Length + p._coefficients.Length - 1];

for (var i = 0; i < newCoefficients.Length; ++i)
{
newCoefficients[i] = 0.0;

var n = Math.Min(u._coefficients.Length, i + 1);
for (var j = Math.Max(0, i + 1 - p._coefficients.Length); j < n; ++j)
{
newCoefficients[i] += u._coefficients[j] * p._coefficients[i - j];
}
}

return new Polynomial(newCoefficients);
}

public Polynomial Differentiate()
{
var degree = Degree;
if (degree == 0)
return new Polynomial(new double[] { 0, 0 });
var result = new double[degree];
for (var i = degree; i > 0; --i)
result[i - 1] = i * _coefficients[i];
return new Polynomial(result);
}
public Polynomial Integrate()
{
var degree = Degree;
if (degree == 0)
return new Polynomial(new double[] { 0, 0 });
var result = new double[degree];
for (var i = degree; i > 0; --i)
result[i - 1] = _coefficients[i] / (i + 1);
return new Polynomial(result);
}

public override string ToString()
{
StringBuilder s = new StringBuilder();
for (var i = 0; i < _coefficients.Length; ++i)
{
if (_coefficients[i] != 0.0)
{
if (s.Length > 0)
{
s.Append(_coefficients[i] < 0.0 ? " - " : " + ");
}
else if (_coefficients[i] < 0.0)
{
s.Append('-');
}

double absAi = Math.Abs(_coefficients[i]);
if (absAi - 1.0 != 0.0)
{
s.Append(absAi).Append(' ');
}

s.Append('x');
if (i > 1)
{
s.Append('^').Append(i);
}
}
}

return s.ToString();
}
}
}```