About Contour plot

What exactly does the circular lines in the contour represent ?
Does every point of an ellipse have same J ?

I assume you are talking about C1 W1 Video: Visualizing the cost function at time 4:17.

It is the cost function value.


Hello @Dhruvil, I see that you changed your first post in this thread with new questions, but please consider to create a reply to this post instead for follow-up questions, because otherwise we won’t be notified of your change and might miss it. Also others who would like to read this post might find it difficult to follow.

So if you are talking about this screenshot,

The answer is yes. Every point along an ellipse has the same J value.


oh yes got it , i’ll keep that in mind .
Also Thanks

You are welcome @Dhruvil !

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i have one doubt here . so these three points(blue, orange, green ) aren’t on the same ellipse here right?

it’s hard to tell by just looking at the contour plot whether they are on the same ellipse or not. I would guess they are not, based on the LHS plot.
however, it should be a snapshot of one of the labs, so you can try that lab to change the positions of those points.

i did try that but i always get different J on the same ellipse . maybe it’s not that precise i guess

Hi @Dhruvil I have this same doubt, since different points on the same ellipse should correspond to the same J, why isn’t this the case in the lab? Is it truely because it’s not precise or some other reason

Hello @chilly_table,

Points on the same contour line has the same cost value. If that doesn’t look that way to you, I would suspect for a precision problem first. Is the cost value too much off, or just very slightly?

Happy new year, and cheers,

Hi @rmwkwok , the cost value is actually off way too much.

Happy New Year,cheers

Hello @chilly_table,

Could you show us what you had seen?


I can see to that those different color points must be on different ellipses , this is observed from plot at LHS and the 3D plot. I guess the RHS plot is not precise and that is the reason it brings all of them together.