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 How: Integration of a Dataset; saving of result??		  New Topic  Reply to Topic
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PHPDQCD

USA
5 Posts
Posted - 07/05/2002 :  08:01:12 AM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Hi,

i have a dataset of two columns, Data_1 is time, Data_2 ist (dq/dt), which is P.
For time t1 the q value is
the integral(start at t0, end at t1) over (dq/dt).

Now I want to plot q vs P. So to get my q values corresponding to the P values, i have to perform an integration for every P value.

How can i do this and put the results into another column?

My idea is to calculate the values of the integrals in a way that this value is defined as the integral over all datapoints of the P values in column data_2 up to this timepoint and store this value in column data_3.

After that I want top plot data_2 vs. data_3.

But I don't know how to do this, especially the integration over the datapoints.

Thank you for your help, regards

Jose

Netherlands
93 Posts
Posted - 07/05/2002 :  09:40:43 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
I do that kind of things using LabTalk like follows. I suppose you have two columns of data, named t and P, and that t is X type and P is Y type. Add another one at the end and name it Data1_Q. Then execute the following in the Script Window:


for (ii=1;ii<=wks.maxrows;ii+=1){
	  integrate %h_P -b 1 -e ii;
	  %h_Q[ii]=integ.area;
}


This assumes that your t0 value is in the first row.

Jose Via, Origin WebRing member
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PHPDQCD

USA
5 Posts
Posted - 07/08/2002 :  07:25:02 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Thank you, thats exactly what i have searched for.
Michael
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