MATLAB . , . , . . : , , . . MATLAB , . , -, , -.
. , =, , , . . ,
V=[1 2 3]
V =
1 2 3
- V, 1,2,3.
: V=[1,2,3] V=[1 2,3] .
<:> () , , .. . :
>> V=-0.1:0.3:1.4
V =
-0.1000 0.2000 0.5000 0.8000 1.1000 1.4000
, , . .
.., , :
x=xn:h:xk
xn ;
xk ;
h .
, 1.
, .
x1=-pi:0.01:pi;
y1=-1.*(x1<=-pi/2) + 0.*(x1>-pi/2 & x1<=pi/2) + 1.*(x1>pi/2);
linspace.
>> u=linspace(3,20,4)
u =
3.0000 8.6667 14.3333 20.0000
, . :
>> V=[2+2/(3+4),exp(5),sqrt(10)]
V =
2.2857 148.4132 3.1623
- A , <;>:
>> A=[1.3;5.4;6.9]
A =
1.3000
5.4000
6.9000
- - ( ).
( A1 A2 ):
>> Q=[A1;A2];
A1 , A2 .
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<;> . , -, . -, ,
B =.
>> B=[1 3 0;-2 -2 5]
B =
1 3 0
-2 -2 5
. . , <Enter>. . , .
B:
>> B=[1 3 0
-2 -2 5]
B =
1 3 0
-2 -2 5
( ), , . V, -
>> V=[3.1 4.5 7.1 2.2 0.8];
, , , :
>> V(3)
ans =
7.1000
, , , π, :
>> V(3)=pi
v =
3.1000 4.5000 3.1416 2.2000 0.8000
end.
>> vx=V(end)
vx =
0.8000
, , , :
>> M=[1 2 3 4;5 6 7 8];
>> M(2,3)
ans =
, 7, , e, :
>> M(2,3)=exp(1)
M =
1.0000 2.0000 3.0000 4.0000
5.0000 6.0000 2.7183 8.0000
, , , .
, . , :
>> A=[1 2]
A =
1 2
>> A(2,3)=5
A =
1 2 0
0 0 5
.
>> A(1,1)/A(1,2)-A(2,3)
ans =
-4.5000
, , , , A(1:5,6:8), 1 5 6 8. (), (A(:,6:8)).
>> A=magic(8)
A =
64 2 3 61 60 6 7 57
9 55 54 12 13 51 50 16
17 47 46 20 21 43 42 24
40 26 27 37 36 30 31 33
32 34 35 29 28 38 39 25
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41 23 22 44 45 19 18 48
49 15 14 52 53 11 10 56
8 58 59 5 4 62 63 1
>> A(:,6:8)
ans =
6 7 57
51 50 16
43 42 24
30 31 33
38 39 25
19 18 48
11 10 56
62 63 1
<:> ():
j:k [j, j+1,..., k]
j:k , j > k, .. []
j:i:k [j, j+i, j+2i,..., k]
j:i:k , i > 0 j > k , i < 0 j < k, i, j k - .
, :
A(:, j) j- A
A(i,:) i- A
A(:,:) . A.
A(j: k) A(j), A(j+1),..., A(k)
A(:, j:k) A(:, j), A(:, j+1),..., A(:, k)
A(:,:, k) k- A.
A(i, j, k,:) A. : A(i, j, k, 1), A(i, j, k, 2), A(i, j, k, 3), ..
A(:) A, -.
doc elmat.
size(B) B, , , :
>> B=[1 2 3;4 5 6];V=[1 2 3];A=[1;2;3];a=5;
>> disp(size(B))
2 3
>> disp(size(V))
1 3
>> disp(size(A))
3 1
>> disp(size(a))
1 1
, B, V, A,a 2×3, 1×3, 3×1, 1×1 .
length(V) V , .. :
>> disp(length(V))
ndims(B) B.
>> disp(ndims(B))
>> disp(ndims(a))
>> disp(ndims(V))
, B, a, V 2 .
MATLAB 2.
:
>> p(1,1,2)=1
p(:,:,1) =
p(:,:,2) =
>> disp(size(p))
1 1 2
>> disp(ndims(p))
, p 3 1×1×2 p(1,1,1) =0 p(1,1,2) =1.
a , <Enter>, disp(a).
whos. , a, b :
>> a= -1.34;
>> b=2.98+3.86i;
c=[1 2 3;-5 6 -1]
c =
1 2 3
-5 6 -1
whos,
>> whos a b c
, .
Name Size Bytes Class
a 1x1 8 double array
b 1x1 16 double array (complex)
c 2x3 48 double array
Class , Bytes , , Size . .
MATLAB , , clc.
. , , , , who, :
>> who
Your variables are:
a b c
clear. ( ), , :
>> clear b
>> who
Your variables are:
a c
Workspace , , whos.
Workspace Variables . . 2.11 c.
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. 2.11
Variables , , , . .
Workspace . , , .. , Open selection ( ) Variables.
>> M=[]
M =
[]
0×0, Variables.
MATLAB , , . , . , , .
, .
() , , , , , MATLAB . , , :
- ;
- .
.
=, D =, B =.
>> A=[0 -2 4;3 2 1];D=[-5 4 2;1 3 1];B=[-1 -2 -3;1 3 1;0 2 2];
>> disp(A+D)
-5 2 6
4 5 2
>> disp(D-A)
-5 6 -2
-2 1 0
>> disp(3*D)
-15 12 6
3 9 3
, , , <'>:
>> disp(A')
0 3
-2 2
4 1
.
<*> . . An×k ( , n k ) Bk×m : , cij - C=AB, i - j - , . .
cij =.
= n×m n m .
>> C=A*B
C =
-2 2 6
-1 2 -5
,
, . , , : U=X*Y' V=X'*Y. Y (), Y ( ). :
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>> x=[1 2 3];y=[4 5 6];
>> v=x*y'
v =
>> v=x'*y
v =
4 5 6
8 10 12
12 15 18
dot.
>> s=dot(x,y)
s =
. MATLAB cross, . :
>> v1=[1 2 3];v2=[4 5 6];
>> cross(v1,v2)
ans =
-3 6 -3
det(B) │ B │ B.
>> d=det(B)
d =
-6
inv(B) , B. B , .
:
>> B1=inv(B)
B1 =
-0.6667 0.3333 -1.1667
0.3333 0.3333 0.3333
-0.3333 -0.3333 0.1667
, , -1 (-1)-1 = B, -1 = -1 = E, E n, B.
B:
>> disp(inv(B1))
-1.0000 -2.0000 -3.0000
1.0000 3.0000 1.0000
0 2.0000 2.0000
B, .. (-1)-1 = B .
>> disp(B*B1)
1.0000 0 0
-0.0000 1.0000 -0.0000
0 0 1.0000
>> disp(B1*B)
1.0000 0 0
0 1.0000 0
0 -0.0000 1.0000
, .. -1 = -1 = E .
>> disp(B^2)
-1 -10 -5
2 9 2
2 10 6
>> disp(B^-1)
-0.6667 0.3333 -1.1667
0.3333 0.3333 0.3333
-0.3333 -0.3333 0.1667
, , <.^>. .
. B D=.
>> D=B^(1/3)
D =
0.5355 + 0.7217i -0.3647 - 0.0000i -0.7244 + 0.7217i
0.2356 - 0.2165i 1.4422 0.2356 - 0.2165i
-0.0355 + 0.1443i 0.3647 1.2244 + 0.1443i
.
>> D^3
ans =
-1.0000 + 0.0000i -2.0000 - 0.0000i -3.0000 + 0.0000i
1.0000 - 0.0000i 3.0000 - 0.0000i 1.0000 - 0.0000i
0.0000 + 0.0000i 2.0000 + 0.0000i 2.0000 - 0.0000i
>> real(ans)
ans =
-1.0000 -2.0000 -3.0000
1.0000 3.0000 1.0000
0.0000 2.0000 2.0000
D3= B , .. D= .
, sqrtm. expm logm.
MATLAB ( ) . < / >, < \ >, . B/A B*inv(A)
X*A=B,
A\B inv(A)*B
A*X=B.
2 | |
zeros(m, n) | ( ) mn. |
ones(m, n) | mn. |
eye(m, n) | mn. |
rand(m, n) | 0 1, mn. |
randn(m, n) | mn, 0 1 ( ). |
reshape(A, n, m) | nm m n , nm. |
tril(A) | |
triu(A) | |
diag(A, n) | , . , , n>0, , n <0 , n=0 . , , . , , (. ). |
() | |
+ - * / \ ^ | . -, - ( , -). . |
inv(A) | |
det(A) | () |
cross(A, B) | |
.*./.\.^ | . , (). . |
size(A) | ( ) ( ). |
sum(A) | |
mean(A) | |
std(A) | |
min(A) max(A) | , |
sort(A) | |
prod(A) |
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. ( , ), n- .