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Integration along a line

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Old   July 20, 2011, 08:19
Default Integration along a line
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Dijun Pan
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Hi all friends,

I have a problem which required the Z coordinate at a polyline and integrate it with respected to x . eg. Z^2dx

How can I create variable which gives me the Z^2 value at the polyline?

Thank you in advance

Dijun
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Old   July 20, 2011, 19:24
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Glenn Horrocks
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Two ideas:

1) Generate a user variable defined as z^2, and integrate that alone the polyline.
2) use a CEL expression like lineInt(z^2)@polyline and calculate it directly. This can be done in the table view.
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Old   July 21, 2011, 06:01
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Dijun Pan
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Quote:
Originally Posted by ghorrocks View Post
Two ideas:

1) Generate a user variable defined as z^2, and integrate that alone the polyline.
2) use a CEL expression like lineInt(z^2)@polyline and calculate it directly. This can be done in the table view.
Hi, Ghorrocks,

thanks for your help again.
But if I use lengthInt()@Polyline 1, the result will be the integration with respected to polyline. I try to use the z^2 in the polyline but integrate it with respected to x.

Regards

Dijun
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Old   July 21, 2011, 08:13
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I see. You might be able to transform the integral into a with respect to length (dl) integral using a chain rule or something like that. Been so long since I have done that sort of stuff I can't remember off the top of my head.

Otherwise export the points of your polyline including XYZ values of the points and then you can do the integration in another package like excel, tecplot or matlab.
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Old   July 22, 2011, 14:12
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Quote:
Originally Posted by ghorrocks View Post
I see. You might be able to transform the integral into a with respect to length (dl) integral using a chain rule or something like that. Been so long since I have done that sort of stuff I can't remember off the top of my head.

Otherwise export the points of your polyline including XYZ values of the points and then you can do the integration in another package like excel, tecplot or matlab.
Thank you very much! I didn't figure out the way you said but I did the integration by using areaInt_z at the surface then divided by the width of the surface
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