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 Is there a template to decide glass transition T?
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flirt

USA
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Posted - 06/07/2005 :  09:50:49 AM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
and other critical values on a curve like start time, temperature etc?
How to draw a tangential curve?
Thanks.

Mike Buess

USA
3037 Posts

Posted - 06/07/2005 :  12:44:56 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
If your X values are evenly spaced you can used LabTalk's derivative function to draw your tangent. The following example assumes your worksheet is A(X), B(Y). Create col C(Y) to hold the tangent line and plot C in the same layer as B. If you want more than one tangent line you'll need a column for each.

kk=100; // draw tangent through point 100
yy0=col(B)[kk]; // y value at that point
tmp=col(B); // create a temporary dataset from col B
deriv tmp; // differentiate
col(C)=0/0; // clear col C
loop (ii,kk-10,kk+10) {
col(C)[ii]=yy0+(ii-kk)*tmp[kk]; // create 10 points on either side of point kk
};
del tmp; // delete temporary dataset

That won't work if your X values are unevenly spaced. In that case Origin C's Curve_derivative function might work. (I haven't tried.)

...Of course the temporary dataset (tmp) holds the derivatives at each point, which might be what you really need.

Mike Buess
Origin WebRing Member

Edited by - Mike Buess on 06/07/2005 12:47:37 PM

Edited by - Mike Buess on 06/07/2005 12:49:05 PM

Edited by - Mike Buess on 06/07/2005 12:52:18 PM

Edited by - Mike Buess on 06/07/2005 3:24:08 PM
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Mike Buess

USA
3037 Posts

Posted - 06/09/2005 :  1:43:43 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
The File Exchange now has a simple tangent add-on for Origin 7.5...

http://www.originlab.com/fileexchange/details.aspx?fid=106

Mike Buess
Origin WebRing Member
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