Which is the best method to find zero ? and choose the max value and plot a graph comproving the zeros.

1 次查看（过去 30 天）

显示更早的评论

Lucas Pollito 2015-11-23

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/257119-which-is-the-best-method-to-find-zero-and-choose-the-max-value-and-plot-a-graph-comproving-the-zer

关闭： Walter Roberson 2015-11-23

在 MATLAB Online 中打开

For a given parameters

ss=0.6;
T=0.1;
g=1;
b=0.5;
 f1 =  @(r)  1 - (b./r).^2 - (g^-2)*((2/15)*(ss)^9 *(1./(r - 1).^9 - 1./(r + 1).^9 - 9./(8*r).*(1./(r - 1).^8 - 1./(r + 1).^8)) -(ss)^3 *(1./(r-1).^3 - 1./(r+1).^3 - 3./(2*r).*(1./(r-1).^2 - 1./(r+1).^2)));

I want to find the r value when

f1 == 0
So, which is the best method ? findzero, fminbnd, newtonraphson ? fsolve ?

i try

a1=  fzerof1,[1.00000001)
assume(r, 'real');
t=vpasolve(1 - (b/r)^2 - (g^-2)*(2/15*[(s/R)]^9 *(1/(r - 1)^9 - 1/(r + 1)^9 - 9/(8* r) *(1/(r - 1)^8 - 1/(r + 1)^8)) - [(s/R)]^3 *(1/(r -1)^3 - 1/(r + 1)^3 - 3/(2* r)* (1/(r - 1)^2 - 1/(r + 1)^2))) == 0,r,[-Inf,Inf]);
t
options=optimset('MaxIter',1e3,'TolFun',1e-10);
t1=fminbnd(func,0.1,15,options);
t1