MATLAB GUI derivative calculator

• MATLAB
In summary, The conversation is about creating a MATLAB GUI to take an input and display its derivative. The user is having trouble with defining the variable and converting it into a symbolic expression. They are also recommended to use Mathematica for symbolic computations. The solution is to use the str2sym function to convert the variable into a symbolic expression before taking the derivative.
TL;DR Summary
Hello All, I am trying to create a MATLAB Gui that works by taking the derivative of a function and displays the result.
Hello!
Happy Sunday, I am trying to create a MATLAB GUI that can take an input ( i am starting out with just one variable) and take its derivative and display the result. I have attached pictures of what my GUI looks like, and also the code I wrote so far.
Let me also describe my method:
1 edit text box whose tag line is "FCN"
1 pushbutton whose tag line is "equalPushButton"
1 static text box whose tag line is "first", the static text box is blue in the picture attached.

I am running into some problems and I think I know why, but cannot seem to figure out how to fix it. Here is what I did
I went to the callback of the pushbutton and added:
syms x (I did this because I was thinking I had to define the variable..?)
a=get(handles.FCN,'string') This is getting the value from the edit text box
b=str2num(diff(a));
set(handles.first,'string',num2str(b));

As an example I would like my program to be able to handle "4x" as an input and when you hit the push button spit out "4" in the static text box (without the quotes).

I believe the problem is somehow I am not telling MATLAB that we have numbers and letters being typed into the edit text box...

I am new to MATLAB and it is pretty difficult to me so any help would be appreciated. The simpler the explanation the better for me.

Thank you!

Attachments

• Derivative .pdf
65.5 KB · Views: 481
• Screenshot (8).png
20.1 KB · Views: 659
Orodruin said:
https://www.mathworks.com/help/symbolic/str2sym.html
Other than that, you cannot just enter 4x. Matlab will want the multiplication operator.

Also, my suggestion is to use Mathematica for symbolic computations and Matlab for what it was made for.
Okay, I will look over that article right now.
I haven't used Mathmatica. I am currently working on a project for my MATLAB project and I need to be able to take derivatives in my program.

Orodruin said:
https://www.mathworks.com/help/symbolic/str2sym.html
Other than that, you cannot just enter 4x. Matlab will want the multiplication operator.

Also, my suggestion is to use Mathematica for symbolic computations and Matlab for what it was made for.
Yeah, unfortunately the documentation that Mathworks has on their site is challenging for me to understand, that's why I'm here asking questions! I assume posting this was supposed to steer me in the right direction of using str2sym somewhere? Would I be using str2sym when I am assigning my "b" variable to be the derivative of my "a" variable (the one the user inputs)?
Thanks

Your variable "a" is a string and not a symbolic expression that can be evaluated. In order to turn it into a symbolic expression, you will need to convert it to one using sym2str, which is what that function is for. If you do not do this, you will not be able to take the derivative of it.

Orodruin said:
Your variable "a" is a string and not a symbolic expression that can be evaluated. In order to turn it into a symbolic expression, you will need to convert it to one using sym2str, which is what that function is for. If you do not do this, you will not be able to take the derivative of it.
Ahhh, okay! I appreciate it. I will let you know how it goes!
Thanks

1. What is a MATLAB GUI derivative calculator?

A MATLAB GUI derivative calculator is a tool that allows users to calculate the derivative of a mathematical function using the MATLAB software. The GUI (Graphical User Interface) aspect of the calculator makes it easier for users to input their desired function and get the derivative calculated for them.

2. How does a MATLAB GUI derivative calculator work?

The calculator uses numerical methods to approximate the derivative of a function at a specific point. It takes in the user's function as input and uses algorithms to calculate the derivative. The GUI aspect allows users to input their function graphically, making it more user-friendly.

3. Is a MATLAB GUI derivative calculator accurate?

Yes, a MATLAB GUI derivative calculator is accurate to a certain extent. The accuracy of the calculator depends on the complexity of the function and the step size used in the calculation. It is important to note that the calculator uses numerical methods, so there may be some small errors in the calculation.

4. Can I use a MATLAB GUI derivative calculator for any type of function?

Yes, a MATLAB GUI derivative calculator can be used for a wide range of functions, including polynomial, trigonometric, exponential, and logarithmic functions. However, the accuracy of the calculation may vary depending on the complexity of the function.

5. Is a MATLAB GUI derivative calculator difficult to use?

No, a MATLAB GUI derivative calculator is designed to be user-friendly and easy to use. The GUI aspect allows users to input their function graphically, making it easier for those who are not familiar with coding to use the calculator. However, some basic knowledge of calculus and MATLAB may be helpful in understanding the results and adjusting the settings for more accurate calculations.

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