Area inscribed by points ?

[JBlackhole]

to all

I have go to sets of data points representing a cross section in an undeformed and deformed state. I would like to get the change of area descbired by the points. I have read the data in mcad and plotted them on a graph. So far so good.

I am struggling with the use of the cspline() and interp() and would appreciate some pointers

Thanks

JXB

[VladimirN]

You forgot to attach the following text files: "test_mcad_und.txt" and "test_mcad_def.txt".

[JBlackhole]

how do I update the original posting?

[MikeArmstrong]

You can click edit on your original post and just post them below.

Mike

[VladimirN]

Use the option "Use advanced editor". See a screenshot:

[Fred_Kohlhepp]

I don't have the file of points, but your approach to the functions is good. See notes and suggestions.

[MikeArmstrong]

Please see this thread. The data is included in there.

http://communities.ptc.com/community/mathcad

Mike

[VladimirN]

Mike,

What do you mean?

[MikeArmstrong]

Jocelyn didn't know how to update a post so he created a new thread and included the data there, have a look at the link I passed.

Mike

[VladimirN]

Thanks. I have seen the new message after some time.

[Tezza2010]

Jocelyn,

Try a different approach. This is a very typical engineering problem. This is how we do it.

It calculates areas of points oriented anyway on a two dimensional plane. It also calculate engineering properties of the area contained with the points like centroid and second moments of area. Input is two arrays on of horizontal coordinate one of matching vertical coordinate values.

You can simply change the file to read a matrix from a file and split into two vectors.

"A" is the area

Regards

Terry

[MikeArmstrong]

Nice example Tezza.

Very interesting way of doing things.

Mike

[Tezza2010]

Mike,

Even can do holes. Just do the hole in the opposite direction and subtract from whole.

Not my idea very old technique.

Regards

Terry

[MikeArmstrong]

Cheers Terry, superb work.

Mike