# how can i bound rate of changes (dx/dt) in fmincon optimization?

7 views (last 30 days)
Ali Barari on 4 Nov 2019
Edited: Matt J on 13 Nov 2019
I need a inequality constraint for (dx/dt<c) in my optimization with fmincon.
i tried many methods,but didnt work.
is there anyone can help me?
##### 0 CommentsShowHide -1 older comments

Sign in to comment.

### Answers (2)

Walter Roberson on 4 Nov 2019
Use the non-linear constraint parameter and have it return (dx/dt - c) . Though if you want a strict inequality rather than <= c then you might need to be a bit careful with the boundary.
##### 4 CommentsShowHide 3 older comments
Walter Roberson on 8 Nov 2019
Create a non-linear inequality that knows the derivative of the function. It is better not to try to estimate it.
fmincon naturally tries to find the zeros of the gradient of the function: when there are no constraints then the minima of a continuous function always satisfies the condition that the gradient is 0 (however, the gradient can also be all zero at maxima or at saddle points.) Therefore unless you have constraints, dx/dt<c will normally be satisfied for positive c.
If you do have constraints then fmincon is still going to be looking for a dx/dt that is as close to zero as feasible, under the constraints
It is therefore not obvious that testing the derivative will do a lot for you, unless c is negative

Sign in to comment.

Matt J on 13 Nov 2019
Edited: Matt J on 13 Nov 2019
##### 0 CommentsShowHide -1 older comments

Sign in to comment.

### Categories

Find more on Get Started with Optimization Toolbox in Help Center and File Exchange

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!