Matlab学习笔记[1](Creating Arrays)
1 CREATING A ONE-DIMENSIONAL ARRAY (VECTOR)
1.1 Creating a vector from a known list of numbers
例子
yr=[1984 1986 1988 1990 1992 1994 1996]
pop=[127; 130; 136; 145; 158; 178; 211]
Row vector
中间可以用space 或者用square brackets(,)号来隔开
Column vector
每一个Column要用semicolon或者用Enter换行隔开
1.2 Creating a vector with constant spacing
variable_name = [m:q:n] Or variable_name = m:q:n
first term is m,last term is n,and the spacing is q
如果加q之后不能达到n，选择离n最近的
If only the first and the last terms，then the default for the spacing is 1
1.3 Creating a vector with linear
variable_name = linspace(xi,xf,n)
xi is First element
xf is Last element
n is Number of elements
When the number of elements is omitted, the default is 100
表示从xi到xf的vector,一共n个数(包括xi,xf)
1.4 CREATING A TWO-DIMENSIONAL ARRAY
variable_name=[1st row elements; 2nd row elements; 3rd row elements; ... ; last row elements]
行之间的用space 或者用square brackets(,)号来隔开
列之间的用semicolon来隔开
create a matrix with m rows and n columns which all elements are the numbers 0
zeros(m,n)
create a matrix with m rows and n columns which all elements are the numbers 1
ones(m,n)
creates a square matrix with n rows and n columns in which the diagonal elements are equal to 1 and the rest of the elements are 0
eyes(n)
1.5 NOTES ABOUT VARIABLES IN MATLAB
在matlab中所有的变量都是数组,分别是scalar,vector and matrix
当变量被分配的时候，不需要分配其大小(before the elements are assigned)
scalar,vector and matrix这三种是可以随便再赋值的
1.6 The transpose operator
方法是X=Y‘
1.7 ARRAY ADDRESSING
1.7.1 Vector
VCT=[35 46 78 23 5 14 81 3 55];
VCT(4);
还可以这样给赋值va(m:n)
u=VCT(3:7)
还可以指定要那些,如
u=v([3, 5, 7:10])
1.7.2 Matrix
MAT=[3 11 6 5; 4 7 10 2; 13 9 0 8];
MAT(3,1)
还可以这样给赋值A(:,n),A(n,:),A(:,m:n),A(m:n,:),A(m:n,p:q)
A=[1 3 5 7 9 11;
2 4 6 8 10 12;
3 6 9 12 15 18;
4 8 12 16 20 24;
5 10 15 20 25 30]
B=A(:,3)
C=A(2,:)
E=A(2:4,:)
F=A(1:3,2:4)
还可以指定要那些,如
B = A([1,3],[1,3,5:7]) 1行，3行，1列，3列，5到7列
1.8 ADDING ELEMENTS TO EXISTING VARIABLES
vector
DF=1:4
DF(5:10)=10:5:35
AD=[5 7 2]
AD(8)=4 (其它地方补零)
AR(5)=24 (直接赋值的，其它地方直接补零)
matrix
E=[1 2 3 4; 5 6 7 8]
加一行
E(3,:)=[10:4:22]
AW=[3 6 9; 8 5 11]
AW(4,5)=17 (其它地方补零)
BG(3,4)=15 (直接赋值的，其它地方直接补零)
1.9 DELETING ELEMENTS
kt=[2 8 40 65 3 55 23 15 75 80]
kt(6)=[]
kt(3:6)=[]
mtr=[5 78 4 24 9; 4 0 36 60 12; 56 13 5 89 3]
mtr(:,2:4)=[]
1.10 BUILT-IN FUNCTIONS FOR HANDLING ARRAYS
length(A)
size(A)
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