.
MATLAB
dx / dt = x 2 + y 2 17,
dy / dt = xy + 4.
:
x 2 + y 2 17 =0,
xy + 4 = 0.
(graf_ik.m):
x=[-sqrt(17):0.001:sqrt(17)];
y1=sqrt(17-x.^2);
y2=-sqrt(17-x.^2);
plot(x,y1,x,y2)
hold on
grid on
x1=[-4.5:0.01:-0.7];
z1=-4./x1;
plot(x1,z1,'.')
x1=[0.7:0.01:4.5];
z1=-4./x1;
plot(x1,z1,'.')
hold off
, , 4, 1, 1 4.
-:
>> x=[-4 -1 1 4];
>> y=-4./x
y =
1 4 -4 -1
, :
4 1
1 4
1 4
4 1
. , F 1(x, y) F 2(x, y) x 0, y 0, :
:
ai,j .
MATLAB jacobian. Symbolic Math Toolbox.
jacobian(f,v)
l,
I MATLAB eig.
f 1 = x 2 + y 2 17 f 2 = x * y + 4 :
>> syms x y
f=[x^2+y^2-17;x*y+4];
v=[x,y];
r=jacobian(f,v)
r =
[ 2*x, 2*y]
[ y, x]
MATLAB subs, eig(), :
>> x=-4; >> y=1; >> a=subs(r) a = -8 2 1 -4 >> eig(a) ans = -8.4495 -3.5505 | >> x=-1; >>y=4; >> a=subs(r) a = -2 8 4 -1 >> eig(a) ans = -7.1789 4.1789 | >> x=1; >> y=-4; >> a=subs(r) a = 2 -8 -4 1 >> eig(a) ans = 7.1789 -4.1789 | >> x=4; >> y=-1; >> a=subs(r) a = 8 -2 -1 4 >> eig(a) ans = 8.4495 3.5505 |
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