sym에서 double로 변환할 수 없다는 오류가 뜨는데 어떻게 해결해야 할까요?

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WOOJIN
WOOJIN 2023-11-13
评论： WOOJIN 2023-11-13
function golden(f,a,b,tolx,toly)
r=(3-sqrt(5))/2;
c=1-r;
x1=a+r*(b-a);
x2=a+c*(b-a);
f1=feval(f,x1);
f2=feval(f,x2);
k=0;
fprintf('\n')
disp(' Golden Section Search ')
fprintf('\n')
disp('_______________________________________________________')
disp('k a x1 x2 b f(x1) f(x2)')
disp('_______________________________________________________')
fprintf('\n')
while (abs(b-a)>tolx)|(abs(f2-f1)>toly)
fprintf('%2.f %10.7f %10.7f %10.7f %10.7f %10.7f %10.7f\n',k,a,x1,x2,b,f1,f2)
if (f1<f2)
b=x2;
x2=x1;
x1=a+r*(b-a);
f2=f1;
f1=feval(f,x1);
else
a=x1;
x1=x2;
x2=a+c*(b-a);
f1=f2;
f2=feval(f,x2);
end
k=k+1;
end
fprintf('\n minimum = %14.10f',f1)
fprintf('at x = %14.10f',b)
function f=trig(x)
f=cos(x)-sin(x)
golden('f',1,3,10^-8,10^-8)을 구하고자 하는데
fprintf('%2.f %10.7f %10.7f %10.7f %10.7f %10.7f %10.7f\n',k,a,x1,x2,b,f1,f2) 여기서 sym에서 double로 변환할 수 없다는 오류가 뜹니다. k,a,x1,x2,b는 출력이 되고 f1,f2가 출력되지 않는 걸 보아 f1,f2에서 오류가 발생한 것 같은데 잘 모르겠습니다.

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采纳的回答

Dyuman Joshi
Dyuman Joshi 2023-11-13
Ran in:
You need to pass the function to be analysed as a function handle -
% vvvvv
golden(@trig,1,3,10^-8,10^-8)
Golden Section Search _______________________________________________________ k a x1 x2 b f(x1) f(x2) _______________________________________________________ 0 1.0000000 1.7639320 2.2360680 3.0000000 -1.1733444 -1.4040220 1 1.7639320 2.2360680 2.5278640 3.0000000 -1.4040220 -1.3934259 2 1.7639320 2.0557281 2.2360680 2.5278640 -1.3508548 -1.4040220 3 2.0557281 2.2360680 2.3475242 2.5278640 -1.4040220 -1.4141604 4 2.2360680 2.3475242 2.4164079 2.5278640 -1.4141604 -1.4116506 5 2.2360680 2.3049517 2.3475242 2.4164079 -1.4123572 -1.4141604 6 2.3049517 2.3475242 2.3738354 2.4164079 -1.4141604 -1.4139935 7 2.3049517 2.3312629 2.3475242 2.3738354 -1.4137741 -1.4141604 8 2.3312629 2.3475242 2.3575742 2.3738354 -1.4141604 -1.4142122 9 2.3475242 2.3575742 2.3637854 2.3738354 -1.4142122 -1.4141728 10 2.3475242 2.3537354 2.3575742 2.3637854 -1.4142093 -1.4142122 11 2.3537354 2.3575742 2.3599466 2.3637854 -1.4142122 -1.4142036 12 2.3537354 2.3561079 2.3575742 2.3599466 -1.4142136 -1.4142122 13 2.3537354 2.3552017 2.3561079 2.3575742 -1.4142129 -1.4142136 14 2.3552017 2.3561079 2.3566679 2.3575742 -1.4142136 -1.4142134 15 2.3552017 2.3557617 2.3561079 2.3566679 -1.4142134 -1.4142136 16 2.3557617 2.3561079 2.3563218 2.3566679 -1.4142136 -1.4142136 17 2.3557617 2.3559757 2.3561079 2.3563218 -1.4142135 -1.4142136 18 2.3559757 2.3561079 2.3561896 2.3563218 -1.4142136 -1.4142136 19 2.3561079 2.3561896 2.3562401 2.3563218 -1.4142136 -1.4142136 20 2.3561079 2.3561584 2.3561896 2.3562401 -1.4142136 -1.4142136 21 2.3561584 2.3561896 2.3562089 2.3562401 -1.4142136 -1.4142136 22 2.3561584 2.3561777 2.3561896 2.3562089 -1.4142136 -1.4142136 23 2.3561777 2.3561896 2.3561970 2.3562089 -1.4142136 -1.4142136 24 2.3561896 2.3561970 2.3562015 2.3562089 -1.4142136 -1.4142136 25 2.3561896 2.3561941 2.3561970 2.3562015 -1.4142136 -1.4142136 26 2.3561896 2.3561924 2.3561941 2.3561970 -1.4142136 -1.4142136 27 2.3561924 2.3561941 2.3561952 2.3561970 -1.4142136 -1.4142136 28 2.3561924 2.3561935 2.3561941 2.3561952 -1.4142136 -1.4142136 29 2.3561935 2.3561941 2.3561946 2.3561952 -1.4142136 -1.4142136 30 2.3561941 2.3561946 2.3561948 2.3561952 -1.4142136 -1.4142136 31 2.3561941 2.3561944 2.3561946 2.3561948 -1.4142136 -1.4142136 32 2.3561944 2.3561946 2.3561947 2.3561948 -1.4142136 -1.4142136 33 2.3561944 2.3561945 2.3561946 2.3561947 -1.4142136 -1.4142136 34 2.3561944 2.3561945 2.3561945 2.3561946 -1.4142136 -1.4142136 35 2.3561945 2.3561945 2.3561945 2.3561946 -1.4142136 -1.4142136 36 2.3561945 2.3561945 2.3561945 2.3561945 -1.4142136 -1.4142136 37 2.3561945 2.3561945 2.3561945 2.3561945 -1.4142136 -1.4142136 38 2.3561945 2.3561945 2.3561945 2.3561945 -1.4142136 -1.4142136 39 2.3561945 2.3561945 2.3561945 2.3561945 -1.4142136 -1.4142136 minimum = -1.4142135624 at x = 2.3561945147
function golden(f,a,b,tolx,toly)
r=(3-sqrt(5))/2;
c=1-r;
x1=a+r*(b-a);
x2=a+c*(b-a);
f1=feval(f,x1);
f2=feval(f,x2);
k=0;
fprintf('\n')
disp(' Golden Section Search ')
fprintf('\n')
disp('_______________________________________________________')
disp('k a x1 x2 b f(x1) f(x2)')
disp('_______________________________________________________')
fprintf('\n')
while (abs(b-a)>tolx)|(abs(f2-f1)>toly)
fprintf('%2.f %10.7f %10.7f %10.7f %10.7f %10.7f %10.7f\n',k,a,x1,x2,b,f1,f2)
if (f1<f2)
b=x2;
x2=x1;
x1=a+r*(b-a);
f2=f1;
f1=feval(f,x1);
else
a=x1;
x1=x2;
x2=a+c*(b-a);
f1=f2;
f2=feval(f,x2);
end
k=k+1;
end
fprintf('\n minimum = %14.10f',f1)
fprintf('\nat x = %14.10f',b)
end
function f=trig(x)
f=cos(x)-sin(x);
end
  7 个评论
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Dyuman Joshi
Dyuman Joshi 2023-11-13
Ran in:
You can define it as an anonymous function, but the functionality behind it is the same.
So, No, there is no other way.
%Anonymous function
f=@(x) cos(x)-sin(x);
%pass it as an input
golden(f,1,3,10^-8,10^-8)
Golden Section Search _______________________________________________________ k a x1 x2 b f(x1) f(x2) _______________________________________________________ 0 1.0000000 1.7639320 2.2360680 3.0000000 -1.1733444 -1.4040220 1 1.7639320 2.2360680 2.5278640 3.0000000 -1.4040220 -1.3934259 2 1.7639320 2.0557281 2.2360680 2.5278640 -1.3508548 -1.4040220 3 2.0557281 2.2360680 2.3475242 2.5278640 -1.4040220 -1.4141604 4 2.2360680 2.3475242 2.4164079 2.5278640 -1.4141604 -1.4116506 5 2.2360680 2.3049517 2.3475242 2.4164079 -1.4123572 -1.4141604 6 2.3049517 2.3475242 2.3738354 2.4164079 -1.4141604 -1.4139935 7 2.3049517 2.3312629 2.3475242 2.3738354 -1.4137741 -1.4141604 8 2.3312629 2.3475242 2.3575742 2.3738354 -1.4141604 -1.4142122 9 2.3475242 2.3575742 2.3637854 2.3738354 -1.4142122 -1.4141728 10 2.3475242 2.3537354 2.3575742 2.3637854 -1.4142093 -1.4142122 11 2.3537354 2.3575742 2.3599466 2.3637854 -1.4142122 -1.4142036 12 2.3537354 2.3561079 2.3575742 2.3599466 -1.4142136 -1.4142122 13 2.3537354 2.3552017 2.3561079 2.3575742 -1.4142129 -1.4142136 14 2.3552017 2.3561079 2.3566679 2.3575742 -1.4142136 -1.4142134 15 2.3552017 2.3557617 2.3561079 2.3566679 -1.4142134 -1.4142136 16 2.3557617 2.3561079 2.3563218 2.3566679 -1.4142136 -1.4142136 17 2.3557617 2.3559757 2.3561079 2.3563218 -1.4142135 -1.4142136 18 2.3559757 2.3561079 2.3561896 2.3563218 -1.4142136 -1.4142136 19 2.3561079 2.3561896 2.3562401 2.3563218 -1.4142136 -1.4142136 20 2.3561079 2.3561584 2.3561896 2.3562401 -1.4142136 -1.4142136 21 2.3561584 2.3561896 2.3562089 2.3562401 -1.4142136 -1.4142136 22 2.3561584 2.3561777 2.3561896 2.3562089 -1.4142136 -1.4142136 23 2.3561777 2.3561896 2.3561970 2.3562089 -1.4142136 -1.4142136 24 2.3561896 2.3561970 2.3562015 2.3562089 -1.4142136 -1.4142136 25 2.3561896 2.3561941 2.3561970 2.3562015 -1.4142136 -1.4142136 26 2.3561896 2.3561924 2.3561941 2.3561970 -1.4142136 -1.4142136 27 2.3561924 2.3561941 2.3561952 2.3561970 -1.4142136 -1.4142136 28 2.3561924 2.3561935 2.3561941 2.3561952 -1.4142136 -1.4142136 29 2.3561935 2.3561941 2.3561946 2.3561952 -1.4142136 -1.4142136 30 2.3561941 2.3561946 2.3561948 2.3561952 -1.4142136 -1.4142136 31 2.3561941 2.3561944 2.3561946 2.3561948 -1.4142136 -1.4142136 32 2.3561944 2.3561946 2.3561947 2.3561948 -1.4142136 -1.4142136 33 2.3561944 2.3561945 2.3561946 2.3561947 -1.4142136 -1.4142136 34 2.3561944 2.3561945 2.3561945 2.3561946 -1.4142136 -1.4142136 35 2.3561945 2.3561945 2.3561945 2.3561946 -1.4142136 -1.4142136 36 2.3561945 2.3561945 2.3561945 2.3561945 -1.4142136 -1.4142136 37 2.3561945 2.3561945 2.3561945 2.3561945 -1.4142136 -1.4142136 38 2.3561945 2.3561945 2.3561945 2.3561945 -1.4142136 -1.4142136 39 2.3561945 2.3561945 2.3561945 2.3561945 -1.4142136 -1.4142136 minimum = -1.4142135624 at x = 2.3561945147
function golden(f,a,b,tolx,toly)
r=(3-sqrt(5))/2;
c=1-r;
x1=a+r*(b-a);
x2=a+c*(b-a);
f1=feval(f,x1);
f2=feval(f,x2);
k=0;
fprintf('\n')
disp(' Golden Section Search ')
fprintf('\n')
disp('_______________________________________________________')
disp('k a x1 x2 b f(x1) f(x2)')
disp('_______________________________________________________')
fprintf('\n')
while (abs(b-a)>tolx)|(abs(f2-f1)>toly)
fprintf('%2.f %10.7f %10.7f %10.7f %10.7f %10.7f %10.7f\n',k,a,x1,x2,b,f1,f2)
if (f1<f2)
b=x2;
x2=x1;
x1=a+r*(b-a);
f2=f1;
f1=feval(f,x1);
else
a=x1;
x1=x2;
x2=a+c*(b-a);
f1=f2;
f2=feval(f,x2);
end
k=k+1;
end
fprintf('\n minimum = %14.10f',f1)
fprintf('\nat x = %14.10f',b)
end
WOOJIN
WOOJIN 2023-11-13
I fully understand, thank u !

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