how to use fzero?

Question

Qasim Manzoor 2013-10-22

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/91090-how-to-use-fzero

评论： Matt J 2013-10-22

the code im trying to run is

m1=input('Enter Mach number=');
y=input('Enter the Specific Heat ratio of working fluid=');
ang=input('Enter theta =');
syms b
t=ang*(pi/180);
f=tan(t)-2*cot(b)*((((m1^2)*(sin(b))^2)-1)/((m1^2*(y+cos(2*b)))+2));   
fzero(f,25)

what i actually need is to find the value of b which makes the function "f" zero where t,m1 and y are numerical values. so i need to solve the above equation for b. any tips how i can do this?

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Answer 1

Matt J 2013-10-22

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https://ww2.mathworks.cn/matlabcentral/answers/91090-how-to-use-fzero#answer_100511

在 MATLAB Online 中打开

Omit the symbolic operations, if you plan to solve numerically

m1=input('Enter Mach number='); 
y=input('Enter the Specific Heat ratio of working fluid=');
ang=input('Enter theta =');
t=ang*(pi/180);
f=@(b) tan(t)-2*cot(b)*((((m1^2)*(sin(b))^2)-1)/((m1^2*(y+cos(2*b)))+2));   
fzero(f,25)

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Qasim Manzoor 2013-10-22

does that mean that fzero isnt compatible with syms?

Matt J 2013-10-22

编辑：Matt J 2013-10-22

That's right, it is not a symbolic solver. For that you would use solve(). However, there doesn't appear to be any reason to be doing symbolic computations in this situation.

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