Matlab与数学建模综合练习(2)

>> B=[5 0;0 5] B =

5 0 0 5

>> C=A*B-B*A C =

0 0 0 0

5．如何建立如下的矩阵（命令方式和程序方式）？

??20040?0?（１）?02004?0?????????；

??00?2004???10?10命令式：

>> D=diag(2004*ones(10,1)) D =

2004 0 0 0 0 0 0 0 2004 0 0 0 0 0 0 0 2004 0 0 0 0 0 0 0 2004 0 0 0 0 0 0 0 2004 0 0 0 0 0 0 0 2004 0 0 0 0 0 0 0 2004 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 程序方式： 建立M文件： A=zeros(10); for i=1:10

for j=1:10 if i==j

A(i,j)=2004;

- 6 -

0 0 0 0 0 0 0 0 0 0 0 0 0 0 2004 0 0 2004 0 0 0 0 0 0 0 0 0 0 0 2004

end end end A

运行结果： A =

2004 0 0 0 0 0 0 0 0 0 0 2004 0 0 0 0 0 0 0 0 0 0 2004 0 0 0 0 0 0 0 0 0 0 2004 0 0 0 0 0 0 0 0 0 0 2004 0 0 0 0 0 0 0 0 0 0 2004 0 0 0 0 0 0 0 0 0 0 2004 0 0 0 0 0 0 0 0 0 0 2004 0 0 0 0 0 0 0 0 0 0 2004 0 0 0 0 0 0 0 0 0 0 2004

??010?10???（２）100?10????????； ??1010?0???10?10命令式：

>> A=10*ones(10) A =

10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10

>> L=tril(A,-1) L =

10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 - 7 -

0 0 0 0 0 0 0 0 0 0

10 0 0 0 0 0 0 0 0 0 10 10 0 0 0 0 0 0 0 0 10 10 10 0 0 0 0 0 0 0 10 10 10 10 0 0 0 0 0 0 10 10 10 10 10 0 0 0 0 0 10 10 10 10 10 10 0 0 0 0 10 10 10 10 10 10 10 0 0 0 10 10 10 10 10 10 10 10 0 0 10 10 10 10

>> U=triu(A,1) U =

0 10 10 10 0 0 10 10 0 0 0 10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

>> L+U

ans =

0 10 10 10 10 0 10 10 10 10 0 10 10 10 10 0 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 程序式：

A=zeros(10); for i=1:10 for j=1:10

10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 0 10 10 0 0 10 0 0 0 0 0 0 0 0 0 0 0 0 10 10 10 10 10 10 10 10 10 10 10 10 0 10 10 10 0 10 10 10 0 10 10 10 10 10 10 10 10 10 10 10 0 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 0 10 10 0 0 10 0 0 0 10 10 10

10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 0 10 10 10 0 10 10 10 0

- 8 -

if i==j

A(i,j)=0; else

A(i,j)=10; end end end A

运行结果: A =

0 10 10 10 10 10 10 10 10 10 0 10 10 10 10 10 …… 此处隐藏：583字，全部文档内容请下载后查看。喜欢就下载吧 ……