symbolic input error in fzero function
显示 更早的评论
function x = ibetainc(y,z,w)
%Inverse of incomplete beta function betainc
zfun = @(x,z,w,y) betainc(x,z,w) - y;
x = fzero(zfun,[0 1],optimset('TolX',1e-5),z,w,y);
end
y = 0.9;
w = 5;
sym z
E = limit((1-ibetainc(y,z,w))*z,z,inf);
I want to calculate the "E". But there is the error.
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Error using fzero (line 246)
FZERO cannot continue because user-supplied function_handle ==> @(x,z,w,y)betainc(x,z,w)-y failed with the error below.
Inputs must be real, full, and double or single.
Error in ibetainc (line 6)
x = fzero(zfun,[0 1],optimset('TolX',1e-5),z,w,y);
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Can I fix this error?
Thank you.
采纳的回答
Alan Weiss
2019-1-29
0 个投票
Your objective function must accept a single scalar argument, not four arguments as you have specified.
Perhaps what you want is to give values to z, w, and y, and compute the single value x. In that case, follow the instructions in Passing Extra Parameters and rewrite your function this way:
function x = ibetainc(y,z,w)
%Inverse of incomplete beta function betainc
zfun = @(x) betainc(x,z,w) - y;
x = fzero(zfun,[0 1]);
end
The z argument must be a regular MATLAB double, not a symbolic variable. Take increasingly small values of z and see what happens.
y = 0.9;
w = 5;
ibetainc(y,0.1,w)
ans =
0.0567
ibetainc(y,0.01,w)
ans =
3.3308e-06
ibetainc(y,0.001,w)
ans =
7.9936e-16
Alan Weiss
MATLAB mathematical toolbox documentation
更多回答（0 个）
类别
在 帮助中心 和 File Exchange 中查找有关 Common Operations 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
