Error using sum function in function handle

2 次查看（过去 30 天）

显示更早的评论

DIMITRIS GEORGIADIS 2021-2-11

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/742597-error-using-sum-function-in-function-handle

评论： DIMITRIS GEORGIADIS 2021-2-14

在 MATLAB Online 中打开

Hi everyone,

Using the following code, I get a matrix dimension error. This is caused only shen using sum inside the function.

% Data
y     = [0.85 0.90]';        % Measurements array m x 1
m       = length(y);
% Function
L    = @(m_x,s_x) (1./s_x.^m).*exp(-0.5.*sum(((y - m_x)./s_x).^2));
% Visualization:
figure
fcontour(L,[0.6 1.4 0.05 0.15])

If I write the function analytically there is no problem.

L    = @(m_x,s_x) (1./s_x.^m).*exp(-0.5.*(((y(1) - m_x)./s_x).^2 + ((y(2) - m_x)./s_x).^2));

Can anyone help me solve this issue?

7 个评论
显示 5更早的评论隐藏 5更早的评论

DIMITRIS GEORGIADIS 2021-2-11

Thank you for your time. I may try a different path

DIMITRIS GEORGIADIS 2021-2-14

在 MATLAB Online 中打开

Turning the function L first to a symbolic expression and then using the "matlabFunction" command fixes the problem.

% Data
y     = [0.85 0.90]';        % Measurements array m x 1
m       = length(y);
% Function
syms m_x s_x
L    = (1./s_x.^m).*exp(-0.5.*sum(((y - m_x)./s_x).^2));
g = matlabFunction(L)
% Visualization:
figure
fcontour(g,[0.6 1.4 0.05 0.15])

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

Steven Lord 2021-2-11

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/742597-error-using-sum-function-in-function-handle#answer_621047

I suspect you have a variable named sum in your workspace when the anonymous function is created. If I'm correct the use of the identifier sum in L will be interpreted as an attempt to index into that variable not as a call to the sum function. Rename that variable.