根据使用的算术类型得出不同的答案(不会发生溢出)
本文关键字:答案 溢出 类型 | 更新日期: 2023-09-27 18:30:51
我在泛型类中有一个函数,用于计算矩阵的行列式。该函数适用于任何类型的某些输入,而对于其他输入,它给出错误的答案(基于类型)。
这是函数:
public T Determinant()
{
checked
{
int n = dimension;
Matrix<T> a = new Matrix<T>(baseArray);
int i, j, k;
T det = (dynamic)0;
for (i = 0; i < n - 1; i++)
{
for (j = i + 1; j < n; j++)
{
det = (dynamic)a[j, i] / a[i, i];
for (k = i; k < n; k++)
a[j, k] = a[j, k] - (dynamic)det * a[i, k];
}
}
det = (dynamic)1;
for (i = 0; i < n; i++)
det = (dynamic)det * a[i, i];
return det;
}
}
我添加了checked
块以查看是否发生了溢出,但显然没有发生溢出。
一个示例输入是,如果 baseArray new double[,] {{11, 11, 12, 17, 21, 29}, {16, 9, 25, 30, 29, 33}, {3, 13, 9, 24, 21,
24}, {23, 6, 29, 21, 23, 23}, {22, 19, 14, 30, 21, 24}, {22, 28,
20, 17, 25, 28}};
它将给出正确的答案(非常接近 -942755),但如果 baseArray 是new int[,] {{11, 11, 12, 17, 21, 29}, {16, 9, 25, 30, 29, 33}, {3, 13, 9, 24, 21,
24}, {23, 6, 29, 21, 23, 23}, {22, 19, 14, 30, 21, 24}, {22, 28,
20, 17, 25, 28}};
则它给出15934050作为答案(甚至不接近)。
上的索引器只返回矩阵的第 i 个第 j 个元素,因此它们不是问题所在。
我对问题可能是什么感到困惑,因为它不是溢出。有什么想法吗?
要重现的代码:
public class Matrix<T>
where T : IConvertible
{
private int dimension;
private T[][] baseArray;
public Matrix(int dimensions, T[,] baseArray)
{
this.dimension = dimensions;
this.baseArray = new T[dimension][];
for (int i = 0; i < dimension; i++)
{
this.baseArray[i] = new T[dimension];
for (int j = 0; j < dimension; j++)
{
this[i, j] = baseArray[i, j];
}
}
}
public T this[int a, int b]
{
get
{
return baseArray[a][b];
}
set
{
baseArray[a][b] = value;
}
}
public T Determinant()
{
checked
{
int n = dimension;
Matrix<T> a = new Matrix<T>(baseArray);
int i, j, k;
T det = (dynamic)0;
for (i = 0; i < n - 1; i++)
{
for (j = i + 1; j < n; j++)
{
det = (dynamic)a[j, i] / a[i, i];
for (k = i; k < n; k++)
a[j, k] = a[j, k] - (dynamic)det * a[i, k];
}
}
det = (dynamic)1;
for (i = 0; i < n; i++)
det = (dynamic)det * a[i, i];
return det;
}
}
}
当值int
值时,它执行整数算术。当值double
值时,它会执行浮点运算 - 就这么简单。更简单的例子:
using System;
public class Test
{
static void Main()
{
PrintResult(1, 2); // Prints 0
PrintResult(1.0, 2.0); // Prints 0.5
}
static void PrintResult(dynamic x, dynamic y)
{
Console.WriteLine(x / y);
}
}