I have this problem Exiting fzero: aborting search for an interval containing a sign change because no sign change is detected during search. Function may not have a root.

Question

Erick 2024-2-26

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2086823-i-have-this-problem-exiting-fzero-aborting-search-for-an-interval-containing-a-sign-change-beca

评论： Walter Roberson 2024-2-26

V3=fzero(@Pr3,0.7);
V3
function y=Pr3(V)
Pr=4;
R=0.08206;
T=450;
Tc=405.5;
Pc=111.3;
P=Pr*Pc;
a=0.42747*((R^2)*Tc^(5/2)/Pc);
b=0.08664*(R*Tc/Pc);
y=((R*T)/(V-b))-(a/(V*(V+b)*T^(1/2)))-P;
end

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Walter Roberson 2024-2-26

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2086823-i-have-this-problem-exiting-fzero-aborting-search-for-an-interval-containing-a-sign-change-beca#answer_1416573

在 MATLAB Online 中打开

syms V

Q = @(v) sym(v);

Pr = Q(4);

R = Q(08206) / Q(10)^5;

T = Q(450);

Tc = Q(405.5);

Pc = Q(1113) / Q(10)^1;

P = Pr*Pc;

a = Q(42747) / Q(10)^5 * ((R^2)*Tc^(5/2)/Pc);

b = Q(08664) / Q(10)^5 * (R*Tc/Pc);

y = ((R*T)/(V-b))-(a/(V*(V+b)*T^(1/2)))-P;

y

y =

sol = solve(y, 'maxdegree', 3)

sol =

vpa(sol)

ans =

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Walter Roberson 2024-2-26

在 MATLAB Online 中打开

format long g
V3=fzero(@Pr3,0.05);
V3
V3 = 
         0.050876353674731
function y=Pr3(V)
Pr=4;
R=0.08206;
T=450;
Tc=405.5;
Pc=111.3;
P=Pr*Pc;
a=0.42747*((R^2)*Tc^(5/2)/Pc);
b=0.08664*(R*Tc/Pc);
y=((R*T)/(V-b))-(a/(V*(V+b)*T^(1/2)))-P;
end