我必须创建一个方法,将给定的Matrix乘以它的转置。
考虑我的矩阵是2d数组double [][] matrix;
public double[][] MultiplyByTranspose(double[][] matrix)
{
return newMatrix;
}
如果您需要我的Matrix课程,请在answer of this question
中查看答案 0 :(得分:1)
嗯,最简单的方法就是实现 Transpose and Multiplication。
当然,当组合时,它可以更高效,但我认为你需要Transpose和Multiplication作为分离的例程进一步在您的代码中(您已经询问矩阵旋转)
public static Boolean IsRectangle(Double[][] value) {
if (Object.ReferenceEquals(null, value))
return false;
else if (value.Length <= 0)
return false;
Double[] line = value[value.Length - 1];
if (Object.ReferenceEquals(null, line))
return false;
int size = line.Length;
for (int i = value.Length - 2; i >= 0; --i)
if (Object.ReferenceEquals(null, value[i]))
return false;
else if (value[i].Length != size)
return false;
return true;
}
public static Double[][] Transpose(Double[][] value) {
if (Object.ReferenceEquals(null, value))
throw new ArgumentNullException("value");
if (!IsRectangle(value))
throw new ArgumentException("value should be a rectangular matrix.", "value");
int colCount = value.Length;
int rowCount = value[value.Length - 1].Length;
Double[][] result = new Double[rowCount][];
for (int i = rowCount - 1; i >= 0; --i) {
Double[] line = new Double[colCount];
result[i] = line;
for (int j = colCount - 1; j >= 0; --j)
line[j] = value[j][i];
}
return result;
}
// Simple quibic algorithm
public static Double[][] Multiply(Double[][] left, Double[][] right) {
if (Object.ReferenceEquals(null, left))
throw new ArgumentNullException("left");
else if (Object.ReferenceEquals(null, right))
throw new ArgumentNullException("right");
if (!IsRectangle(left))
throw new ArgumentException("left should be a rectangular matrix", "left");
else if (!IsRectangle(right))
throw new ArgumentException("right should be a rectangular matrix", "right");
int leftRows = left.Length;
int leftCols = left[0].Length;
int rightRows = right.Length;
int rightCols = right[0].Length;
if (leftCols != rightRows)
throw new ArgumentOutOfRangeException("right");
Double[][] result = new Double[leftRows][];
for (int r = leftRows - 1; r >= 0; --r) {
Double[] leftLine = left[r];
Double[] line = new Double[rightCols];
result[r] = line;
for (int c = rightCols - 1; c >= 0; --c) {
Double s = 0.0;
for (int i = leftCols - 1; i >= 0; --i)
s += leftLine[i] * right[i][c];
line[c] = s;
}
}
return result;
}
...
public double[][] MultiplyByTranspose(double[][] matrix) {
//TODO: Check the order! Which matrix should be the first and which the second,
// In Linear Algebra A * B != B * A
return Multiply(matrix, Transpose(matrix));
// Or
// return Multiply(Transpose(matrix), matrix);
}