如何查询matlab命令
方法1 Google搜索:matlab xxx
方法2 command window输入
查询所有变量
who: 只显示变量名
whos: 显示所有变量详细信息
matlab关键字优先级
变量 > 内置程序 > 自定义程序 > private function
矩阵
行向量: a = [1 2 3 4]
列向量:b = [1; 2; 3; 4]
a(3) = 3 b(4) = 4
A = [1 2 3; 4 5 6; 7 8 9]
A(1,2)=2
A(4)=2
A([1 3 5])=[1 7 5]
A([1 3;1 3])=[1 7;1 7]
A([1 3], [1 3])=[1 3;7 9]
A(3,:)=[7 8 9]
A(3,:)=[] 删除第三行
===分割线===
A = [1 2;3 4] B = [9 9;9 9]
F = [A B] = [A, B] = [1 2 9 9; 3 4 9 9]
E = [A; B] = [1 2;3 4;9 9;9 9]
切片
A = 1:100
B = 1:2:100(第二个是步长)
C=[1:5; 2:3:15; -2:0.5:0]
矩阵运算
A+B
A-B
A*B
A.*B
A./B
A+a
A/a <=> A./a
A^a
A.^a
A'
eye(n):n*n的单位矩阵
zeros(n1, n2): n1*n2的0矩阵
diag([1,2,3])=[1 0 0;0 2 0;0 0 3]
===分割线===
A = [1 2 3;0 5 6;7 0 9]
max(A) = [7 5 9]
max(max(A)) = 9
min同理
sum(A) = [8 7 18]
mean(A) = [2.6667 2.3333 6.0000]
sort(A) = [0 0 3;1 2 6;7 5 9] (即每列分别排序)
sortrows(A) = [0 5 6;1 2 3;7 0 9] (按字典序、以行为单位对矩阵排序)
size(A) = [3 3]
find(A==5) = 5 find(A==6) = 8