2018-11-28 MF -- LU factorization

1 --- LU 矩阵分解

参考自matlab官方教程。

https://ww2.mathworks.cn/help/matlab/ref/lu.html?lang=en#mw_541f2442-eeb4-42d5-a121-6e7e7fa3087f

The main idea of LU-MF is A=LU, note the diagnial of L is 1, and L is a upper triangular matrix. So, U is a lower triangular matrix.

When applying the official tutorial, i have a question. How to use the Subplot function? 

The official description is subplot(m,n,p) divides the current figure into an m-by-n grid and creates axes in the position specified by p. MATLAB® numbers subplot positions by row. The first subplot is the first column of the first row, the second subplot is the second column of the first row, and so on. If axes exist in the specified position, then this command makes the axes the current axes.

Understand.    

Following is the example of LU.

Firstly, give the input matrix. 

A = [10 -7 0

    -3  2 6

      5 -1 5];

Then, apply one kind of the LU function. 

For ease of understand, we use the subplot to plot the L matrix and U matrix.