how to use anonymous function with equation without retype the all equation?

Question

Abdulaziz Abutunis 2017-3-21

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/331116-how-to-use-anonymous-function-with-equation-without-retype-the-all-equation

评论： Walter Roberson 2017-3-21

Dear all,

does anyone know how to use the anonymous function with equation that already defined without type it again. For example,eq1 = x^2+3+y^3; sol=@(x,y) eq1. I tried eq1(2,2) but it does not work as wished. Please help

Best regards, Aziz

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

Matt J 2017-3-21

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/331116-how-to-use-anonymous-function-with-equation-without-retype-the-all-equation#answer_259730

编辑：Matt J 2017-3-21

在 MATLAB Online 中打开

If x, y and eq1 are symbolic variables, then there is no reason to be wrapping eq1 in an anonymous function. Just use the subs() command to evaluate eq1 at desired values. E.g.,

    >> syms x y
    >> eq1 = x^2+3+y^3
    eq1 =
    x^2 + y^3 + 3
    >> val=double(subs(eq1,[x,y],[2,2]))
    val =
        15

If you insist on wrapping it in anonymous function, you could do something like,

sol=@(a,b) double(subs(eq1,[x,y],[a,b]))

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Walter Roberson 2017-3-21

If you are starting from symbolic expressions, then use matlabFunction() to create function handles for numeric processing.

请先登录，再进行评论。

Answer 2

Stephen23 2017-3-21

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/331116-how-to-use-anonymous-function-with-equation-without-retype-the-all-equation#answer_259713

编辑：Stephen23 2017-3-21

在 MATLAB Online 中打开

 >> sol = @(x,y)x^2+3+y^3;
 >> sol(2,2)
 ans =
     15

exactly as the documentation shows:

https://www.mathworks.com/help/matlab/matlab_prog/anonymous-functions.html

3 个评论
显示 1更早的评论隐藏 1更早的评论

James Tursa 2017-3-21

Then please show us more detail about your problem. Where is the equation coming from? What is this iterative process doing? Etc.

Abdulaziz Abutunis 2017-3-21

not necessary info for the question..if there is no way to do it then i will switch to another technique

请先登录，再进行评论。

Answer 3

Steven Lord 2017-3-21

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/331116-how-to-use-anonymous-function-with-equation-without-retype-the-all-equation#answer_259721

在 MATLAB Online 中打开

As written, eq1 is not an equation. x and y must be defined before you execute "eq1 = x^2+3+y^3;" or you will receive an error. If you want to define the equation once and use it later, execute:

sol = @(x,y) x.^2+3+y.^3;

Note I used .^ so you can call sol with a nonscalar array, not just a scalar. If you need eq1 to be the value of that function for specific values of x and y:

eq1 = sol(2, 2)