# Radius and centre of curvature

8 views (last 30 days)
Subramani Nagaraj on 18 Jan 2021
Commented: Image Analyst on 29 Jan 2023
Can anyone say
why it is showing inf as output as shown in the screenshot attached, when I ask radius and centre of curvature for sqrt(X)+sqrt(y)==sqrt(a),when x = 3???
Why it is not showing a numerical value???
Kindly solve this problem.
KALYAN ACHARJYA on 18 Jan 2021
Maybe you forgot to attach the screenshot?
Subramani Nagaraj on 19 Jan 2021
Edited: Subramani Nagaraj on 19 Jan 2021
Sorry sir I thought I had attached the screenshot. Now I had attached it.

Divija Aleti on 25 Jan 2021
Hi Nagaraj,
You will have to first change your equation to the form of y = f(x) and then use the formulae to find the radius and center of curvature. The code is given below for your reference:
syms y(x) a
y(x) = (sqrt(a)-sqrt(x))^2; % Re-arranged the equation
x1 = 3;
c1 = x - (diff(y,x)*(1+(diff(y,x))^2))/diff(y,x,2);
c1 = c1(x1) % Found x-coordinate of center of curvature
y1 = y(x1);
c2 = y + (1+(diff(y,x))^2)/diff(y,x,2);
c2 = c2(y1) % Found y-coordinate of center of curvature
Center = [c1,c2];
Point = [x1,y1];
Radius = ((x1-c1)^2 + (y1-c2)^2) % Distance between the point and the center gives radius of curvature
For additional information on the 'diff' function, refer to the following link:
Regards,
Divija
##### 3 CommentsShow 1 older commentHide 1 older comment
Image Analyst on 28 Jan 2023
If you have any more questions, then attach your data and code to read it in with the paperclip icon, in a new question, after you read this:
Image Analyst on 29 Jan 2023
@Divya I think you ignored my last comment totally. Let me give instructions step by step.
2. Click on the Ask link above (right under the blue MATLAB Answers banner) and fill out the form to post a totally new question (not here).
3. In the edit box, click the paperclip icon and attach your .m file, and any data files that need to be read in.
4. Click the "Post Question" button to submit your question. Then it will appear on the list.

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