/**
* 实现矩阵的乘法
*
* @param other - 与指定矩阵相乘的矩阵
* @return Matrix型，指定矩阵与other相乘之积
* @如果矩阵的行/列数不匹配，则会抛出异常
*/
public Matrix Multiply(Matrix other)
{
// 首先检查行列数是否符合要求
if (numColumns != other.GetNumRows())
{
throw new Exception("矩阵的行/列数不匹配。");
}
// ruct the object we are going to return
Matrix result = new Matrix(numRows, other.GetNumColumns());
// 矩阵乘法，即
//
// [A][B][C] [G][H] [A*G + B*I + C*K][A*H + B*J + C*L]
// [D][E][F] * [I][J] = [D*G + E*I + F*K][D*H + E*J + F*L]
// [K][L]
//
double value;
for (int i = 0; i < result.GetNumRows(); ++i)
{
for (int j = 0; j < other.GetNumColumns(); ++j)
{
value = 0.0;
for (int k = 0; k < numColumns; ++k)
{
value += GetElement(i, k) * other.GetElement(k, j);
}
result.SetElement(i, j, value);
}
}
return(result);
}
/**
* 判断矩阵否相等
*
* @param other - 用于比较的矩阵
* @return bool 型，两个矩阵相等则为true，否则为false
*/
public override bool Equals(object other)
{
Matrix matrix = other as Matrix;
if (matrix == null)
{
return(false);
}
// 首先检查行列数是否相等
if (numColumns != matrix.GetNumColumns() || numRows != matrix.GetNumRows())
{
return(false);
}
for (int i = 0; i < numRows; ++i)
{
for (int j = 0; j < numColumns; ++j)
{
if (Math.Abs(GetElement(i, j) - matrix.GetElement(i, j)) > eps)
{
return(false);
}
}
}
return(true);
}
/**
* 拷贝构造函数
*
* @param other - 源矩阵
*/
public Matrix(Matrix other)
{
numColumns = other.GetNumColumns();
numRows = other.GetNumRows();
Init(numRows, numColumns);
SetData(other.elements);
}
/**
* 给矩阵赋值
*
* @param other - 用于给矩阵赋值的源矩阵
* @return Matrix型，阵与other相等
*/
public Matrix SetValue(Matrix other)
{
if (other != this)
{
Init(other.GetNumRows(), other.GetNumColumns());
SetData(other.elements);
}
// finally return a reference to ourselves
return(this);
}
/**
* 实现矩阵的减法
*
* @param other - 与指定矩阵相减的矩阵
* @return Matrix型，指定矩阵与other相减之差
* @如果矩阵的行/列数不匹配，则会抛出异常
*/
public Matrix Subtract(Matrix other)
{
if (numColumns != other.GetNumColumns() ||
numRows != other.GetNumRows())
{
throw new Exception("矩阵的行/列数不匹配。");
}
// 构造结果矩阵
Matrix result = new Matrix(this); // 拷贝构造
// 进行减法操作
for (int i = 0; i < numRows; ++i)
{
for (int j = 0; j < numColumns; ++j)
{
result.SetElement(i, j, result.GetElement(i, j) - other.GetElement(i, j));
}
}
return(result);
}
/**
* 实现矩阵的加法
*
* @param other - 与指定矩阵相加的矩阵
* @return Matrix型，指定矩阵与other相加之和
* @如果矩阵的行/列数不匹配，则会抛出异常
*/
public Matrix Add(Matrix other)
{
// 首先检查行列数是否相等
if (numColumns != other.GetNumColumns() ||
numRows != other.GetNumRows())
{
throw new Exception("矩阵的行/列数不匹配。");
}
// 构造结果矩阵
Matrix result = new Matrix(this); // 拷贝构造
// 矩阵加法
for (int i = 0; i < numRows; ++i)
{
for (int j = 0; j < numColumns; ++j)
{
result.SetElement(i, j, result.GetElement(i, j) + other.GetElement(i, j));
}
}
return(result);
}
