我如何从左下角到右上角对角线添加一个矩阵int [，]的值? [英] How could I add the values of a matrix int[,] diagonally from bottomleft, to topright?

问题描述

如何从左下角到右上角将矩阵int [，]的值相加?

How could I add the values of a matrix int[,] diagonally from bottomleft, to topright?

我正试图帮助一位朋友理解这一点，但是即使我真的不明白他们在做什么.

I'm trying to help out a friend understand this but even I don't really get what they're doing here.

这是我想向他解释的方法:

Here's the method I'm trying to explain to him:

public void AddDiagonal()
{
    int Addition;

    for (int f = 0; f < filas; f++)
    {
        for (int c = 0; c < columnas; c++)
        {
            if (f == columnas - c - 1)
            {
                Addition += matriz[f, c];
            }
        }
    }
}

推荐答案

了解这一点的关键是if语句:

The key to understanding this is the if statement:

if (f == columnas - c - 1)

两个嵌套循环遍历行(使用f作为索引)，并为每一行遍历列(使用c作为索引).

The two nested loops iterate over rows (using f as an index) and for each row, over columns (using c as an index).

因此，每次迭代时，您都要测试行号(即f)是否等于反转的列号(即从列总数中减去c-).测试列号反转的原因是因为您要从左下至右上添加，这与从右上至左下添加相同.

So each iteration, you test if the row number (that is f) is equal to the column number reversed (that is c subtracted from the total number of columns - columnas). The reason you test for the column number reversed is because you want to add from bottom left to top right, which is the same as adding from top-right to bottom left.

要注意的一件事是，对角矩阵仅对方矩阵有意义，这意味着列数必须与行数相同(在您的算法中，filas应等于columnas).

One thing to note is that a matrix diagonal only makes sense for a square matrix which means the number of columns needs to be same as the number of rows (in your algorithm filas should equal columnas).

因此，假设一个5x5矩阵:

So, assuming a 5x5 matrix:

行0(f = 0)->列4(c = 5-0-1)
第1行(f = 1)->第3列(c = 5-1-1)
第2行(f = 2)->第2列(c = 5-2-1)
第3行(f = 3)->第1列(c = 5-3-1)
第4行(f = 4)->列0(c = 5-4-1)

Row 0 (f = 0) --> Column 4 (c = 5 - 0 - 1)
Row 1 (f = 1) --> Column 3 (c = 5 - 1 - 1)
Row 2 (f = 2) --> Column 2 (c = 5 - 2 - 1)
Row 3 (f = 3) --> Column 1 (c = 5 - 3 - 1)
Row 4 (f = 4) --> Column 0 (c = 5 - 4 - 1)

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