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 Roots of a polynom equation		  New Topic  Reply to Topic
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JokerOne

Germany
58 Posts
Posted - 02/18/2016 :  11:17:01 AM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Origin Ver. 9 and Service Release 1(Select Help-->About Origin):
Operating System: Win 7

Is there a LabTalk Command that provides the root of a polynom-equation, like
3x^3 -7.1527x = 0
to solve for all x that fulfills this equation.

e.g.:
dataset roots
coeff[1] = 3
coeff[2] = 0
coeff[3] = -7.1527
coeff[4] = 0
roots = find_roots(coeff)

The function is suppose to also work for polynom equation of higher order.

As as option, is there an option to investiage a polynom for maximum/minimum condition, etc?

Thanks for your help.

Hideo Fujii

USA
1582 Posts
Posted - 02/18/2016 :  2:15:43 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi JokerOne,

> Is there a LabTalk Command that provides the root of a polynom-equation, like
> 3x^3 -7.1527x = 0

To solve this numerically, the following should do that task:
col(1)=data(-100,100, 0.05);
col(2)=3*col(1)^3 -7.1527*col(1);
levelcrossing iy:=col(2) level:=0;
Hope this helps.

--Hideo Fujii
OriginLab
Edited by - Hideo Fujii on 02/18/2016 2:58:56 PM
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JokerOne

Germany
58 Posts
Posted - 02/19/2016 :  05:56:06 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Thanks again,

may I continue with a question refering:

I would prefer, to store the result, i.e., the roots in a dataset rather than in a particular worksheet.
If I get the documentation correctly, this will then be called a loose dataset?
I tried to do this, but my syntax is properly not correct

dataset bbb;
col(2)=3*col(1)^3 -7.1527*col(1);
levelcrossing iy:=col(2) level:=0 oy:=bbb;
bbb[1]= [does not work]
bbb[2]= [does not work]

also, maybe, I cannot put the result of the the levelcrossing function in a dataset? When the documentation requests an "Output Vector" as datatype, is a [loose?-]dataset allowed?

Maybe, I can store the results in bbb, but I did not manage to access the dataset correctly?
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JokerOne

Germany
58 Posts
Posted - 02/19/2016 :  06:57:00 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
I guess, that I found the correct syntax now.

I had an issue with providing the XYRange in levelcrossing correctly, at least that is what I am thinking.

Thanks again for the hint for the levelcrossing function, this is very helpful.
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Hideo Fujii

USA
1582 Posts
Posted - 02/19/2016 :  09:58:46 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi,

As a reference for public, the following is the workable code:
col(1)=data(-100,100, 0.05);
col(2)=3*col(1)^3 -7.1527*col(1);
range bbb = [??]!loose_a;  //to define the range of a loose dataset
levelcrossing iy:=col(2) level:=0 oy:=bbb;
bbb[1]=;
You can read the details about the loose dataset at:
http://www.originlab.com/doc/LabTalk/guide/Range-Notation#Loose_Dataset

--Hideo Fujii
OriginLab

P.S. You can also write the range string of the loose dataset in the x-function like:
levelcrossing iy:=col(2) level:=0 oy:=[??]!loose_a;
loose_a[1]=;
Edited by - Hideo Fujii on 02/19/2016 10:04:57 AM
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