find the inflection point of a curve 3D (set of nodes) in matlab

How can I determine the inflection point of a set of nodes generating a curve in 3D space?

load curve_1.mat
curve_x = curve_1;
figure
plot3(curve_x(:,1),curve_x(:,2),curve_x(:,3),'k.','Markersize',10)
hold on
plot3(curve_x(:,1),curve_x(:,2),curve_x(:,3),'-r','LineWidth',2)
hold off
grid off
axis equal

Before determining the inflection points, is it possible to make the curve ‘curve_x’ smoother (more like a curve) since the nodes are not placed at a certain distance from each other?

Answer 1

[Matt J]

You can use csaps to fit a smoothing spline to the points and then fnder to differentiate the curve and observe curvature changes.

[Alberto Acri]

Thank you for your reply!

'csaps' I had seen;

'fnder' I wouldn't know where to start. Do you have any ideas?

[Matt J]

You can use the output of csaps directly with fnder,

https://www.mathworks.com/help/curvefit/fnder.html#mw_2bb65204-fdfb-4c10-bb18-cda582b7a632

[Alberto Acri]

Thank you but I could not find a solution. Isn't there a code I can try to use for this case?

[Matt J]

There is the curvature() command in this FEX submission, but I have never used it:

https://www.mathworks.com/matlabcentral/fileexchange/69452-curvature-of-a-1d-curve-in-a-2d-or-3d-space?s_tid=srchtitle