( ) f(x)=0, f(x) x. , f(x)=0 f(x) , .. f(x).
MATLAB fzero:
fzero(hFunction,x0)
hFunction , ; x0 (, x0 , , [x0s x0f] ( x0s<x0f), , , hFunction , ).
fzero , hFunction x0.
. x0=pi/4. :
>> x0=pi/4;
>> x=fzero(@sin,x0)
x =
8.4566e-28
, , 0. @ .
, MATLAB (.. MATLAB ), inline, , :
>> f=inline('sin(x)-x','x')
f =
Inline function:
f(x) = sin(x)-x
>> x=fzero(f,pi/4)
x =
-1.6901e-08
>> f(x)
ans =
, , . . , ,
function y=MyFunction(x)
y=sin(x)-x
fzero:
>> x=fzero(@MyFunction,pi/4)
, ,
>> x=fzero('MyFunction',pi/4)
, fzero, :
>> fzero(hFunction,x0,options)
options fzero, , , options optimset:
>> options=optimset('TolX',1e-8)
optimset TolX ( Tolerance of X; ), ().
|
|
>> options=optimset('TolX',1e-3);
>> x=fzero(f,pi/4)
x =
-1.6901e-08
>> x=fzero(f,pi/4,options)
x =
-2.2912e-04
>> f(x)
ans =
2.0048e-12
>> options=optimset('TolX',1e-8);
>> x=fzero(f,pi/4,options)
x =
-2.1238e-08
>> f(x)
ans =
(). MATLAB roots, . , , :
>> Coeff=[1 -3 3 -3 2]
Coeff =
1 -3 3 -3 2
>> r=roots(Coeff)
r =
2.0000 + 0.0000i
0.0000 + 1.0000i
0.0000 - 1.0000i
1.0000 + 0.0000i
.. (1.0 2.0) ( ), .
fzero . , , , fplot, :
fplot(hFunction,[x0 xl])
hFunction, @name (name ) x0 xl. , (. 2.20.1):
>> fplot(f,[-pi/2,pi/2])
>> fplot(@MyFunction,[-pi/2,pi/2])
>> fplot('MyFunction',[-pi/2,pi/2])
, F(x)=0 ( x ; F , ) MATLAB fsolve. MATLAB.