Trouble taking the differential of a function

Question

Raymond Elliott 2021-2-23

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链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/753289-trouble-taking-the-differential-of-a-function

回答： Star Strider 2021-2-23

I have the following code:

func =@(x) (((w_0*L)/(3*(pi^4)*E*I))*48*(L^3)*cos((pi*x)/(2*L))-48*(L^3)+(3*(pi^3)*L*(x^2))-((pi^3)*(x^3)));
dfunc = diff(func);

However, whenever I try to fun the code I get the following error, "Check for missing argument or incorrect argument data type in call to function 'diff'." What am I missing here?

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Answer 1

Star Strider 2021-2-23

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/753289-trouble-taking-the-differential-of-a-function#answer_630629

在 MATLAB Online 中打开

‘What am I missing here?’

Most likely, using the Symbolic Math Toolbox.

Try this:

syms E I L w_0 x 
func(x) = (((w_0*L)/(3*(pi^4)*E*I))*48*(L^3)*cos((pi*x)/(2*L))-48*(L^3)+(3*(pi^3)*L*(x^2))-((pi^3)*(x^3)));
dfunc = matlabFunction(simplify(diff(func,x), 500));

Note that ‘dfunc’ is now an anonymous function that can be used in numeric calculations outside of the Symbolic Math Toolbox.