Other alternative than syms for differentiation and integration?

Hello Everyone,

I'm trying to use differentiation in Matlab using this code

syms X;
fun = x^3+2*x+10;
diff (fun,x);

But I got this error

"Undefined function 'syms' for input arguments of type 'char'.

Error in Diff_Integ (line 1)

syms X;"

Is there any alternative ways to use differentiation without using syms?

Answer 1

[Star Strider]

MATLAB is case-sensitive, so X ~= x.

Try this:

syms x;
fun = x^3+2*x+10;
dfundx = diff (fun,x);

producing:

dfundx =
3*x^2 + 2

[Muhammad Fakhruddin Abd Rahim]

Same error because

[Star Strider]

You need to purchase, download and install the Symbolic Math Toolbox to use its functions.

Otherwise, to do numerical differentiation, use the gradient fucntion, and to do numerical integration, use the integral function (and its friends).

[Muhammad Fakhruddin Abd Rahim]

Can you guide me how to use the gradient fucntion, and to do numerical integration, use the integral function (and its friends). ?

[Walter Roberson]

f = @(x) x.^3+2*x+10;
area = integral(f, 11, 26)    % integrate from 11 to 26

note that numeric integral is only ever definite integral, fixed numeric bounds for 1D case (for 2D case, the second series of bounds can depend upon the first series of bounds.)

More numeric integration:

f = @(x) x.^3+2*x+10;
X = linspace(11,26);
Y = f(X);
area = cumtrapz(X, Y)

[Muhammad Fakhruddin Abd Rahim]

It's look complicated ^-^

[Walter Roberson]

Some of the details about function handles (begining with @) are complicated, but most people will only encounter a small number of the details. One of the most important ones is discussed at http://www.mathworks.com/help/matlab/math/parameterizing-functions.html

[Muhammad Fakhruddin Abd Rahim]

do you have an english version?

[Walter Roberson]

Go to the bottom of this page you are looking at. The very bottom line gives a copyright. The line above that gives some links starting with Patents. Just above that there is an oval with a globe icon and the name of a country. Click on that button and select United States on the pages that comes up. After that documentation should come up in English.

Note: if you happen to be inside China, then I cannot be sure that you can reach English documentation.

[Stephen23]

"do you have an english version?"

• scroll to the bottom of this page.
• click on this button: (the text inside might be in chinese/whatever language, but there is only one button that looks like this).
• select a country which uses English.

[Star Strider]

@Muhammad Fakhruddin Abd Rahim — I was not ignoring you. I was sleeping.

@Walter — Thank you for following up with your Comments.

@Stephen — Thank you for following up with your Comments.

[Muhammad Fakhruddin Abd Rahim]

thank you sir

[Star Strider]

Our pleasure.

Answer 2

[Walter Roberson]

https://www.mathworks.com/help/matlab/ref/polyder.html for the special case of polynomials.

[Muhammad Fakhruddin Abd Rahim]

It's in chinese