sym에서 double로 변환할 수 없다는 오류가 뜨는데 어떻게 해결해야 할까요?

2023 11 13
1 个回答
回答已采纳
更新时间：2023 11 13
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0 个投票

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:

0 个投票

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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WOOJIN
WOOJIN 2023-11-13
thank u bro !
Dyuman Joshi
Dyuman Joshi 2023-11-13
You are welcome!
WOOJIN
WOOJIN 2023-11-13
how can I pass the function without using '@'? I saved the fuction golden() as golden.m and function f=trig(x) as trig.m. (it means I saved those 2 functions in each other m-file)
Dyuman Joshi
Dyuman Joshi 2023-11-13
"how can I pass the function without using '@'? "
You can not. Why do you ask? Do you get an error?
Even if you have saved the functions separately, this syntax should work. Just make sure that the files are present in the current directory/folder.
WOOJIN
WOOJIN 2023-11-13
No, I got the correct output. I just wondering that is there another way to pass the function not using '@'.
Dyuman Joshi
Dyuman Joshi 2023-11-13
Ran in:
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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