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Meilongwei
China
5 Posts |
 Posted - 04/15/2015 : 11:47:04 AM
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Dear all:
I have another question.
My function is too long and could be express three short product as follows:
y=A*B*C
A=a1*x+b1^x+x^c1+d1
B=a2*x+b2^x+x^c2+d2
C=a3*x+b3^x+x^c3+d3
Here a1,b1,c1，a2,b2,c2，a3,b3,c3 are parameters I need fit.
I tried with C code form but failed.
How could I write such express?
Is Amanda here?
Thanks!
meilongwei |
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jasonzhao
China
262 Posts |
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Meilongwei
China
5 Posts |
Posted - 04/16/2015 : 12:13:32 PM
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quote:
Originally posted by jasonzhao
Hello,
You can refer to this tutorial for more information
http://www.originlab.com/doc/Tutorials/UserDef-FitFunc
The Derived Parameters is used in fitting.
Best regards!
Jason
OriginLab Technical Service
Hi Jason!
I clicked the link you attached, it just shows how to define general function for fitting. But my function is too long to write in oring C.It should be write as follows:
y=A*B*C+A*B+A*C+A/B+B*C+3A...(more complex than this)
A=a1*x+b1^x+x^c1+d1+exp(x^e1)
B=a2*x+b2^x+x^c2+d2+exp(x^e2)
C=a3*x+b3^x+x^c3+d3+exp(x^e3)
a1, b1,... a2, b2...are parameters need to be fitting. A, B, C are intermediate terms for shorten y expression. I mean during express y, A B C is necessary. So how to write it correctly?
Thank you !
meilongwei |
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snowli
USA
1379 Posts |
Posted - 04/16/2015 : 12:37:28 PM
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Hello,
In Fitting Function Builder, you can choose Function Type to be Equation. Then you can split the functions into multiple lines.
But remember to put the final y=..... at the end instead of at the beginning.
The hint on left panel says
---------------------------------------------------------
Function Type
---------------------------------------------------------
Select this option if you need multiple lines or you have more than one dependent variable.
This option does not support control structures such as loops or if-else statements. You can however use the ternary operator.
This option provides faster performance than Origin C.
-------------------- Example1: --------------------
temp = 10;
y1 = A + exp( (x1 - xc) / temp^2 );
y2 = A + temp / (x2 - xc)^2;
-------------------- Example2: --------------------
B = A / (0.5 * (sig1+sig2) * sqrt(2*pi));
sig = ( x<xc ? sig1:sig2 );
y = y0 + B * exp(-0.5 * ((x-xc)/sig)^2);
Thanks, Snow |
Edited by - snowli on 04/16/2015 12:42:09 PM |
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Meilongwei
China
5 Posts |
Posted - 04/16/2015 : 10:05:22 PM
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quote:
Originally posted by snowli
Hello,
In Fitting Function Builder, you can choose Function Type to be Equation. Then you can split the functions into multiple lines.
But remember to put the final y=..... at the end instead of at the beginning.
The hint on left panel says
---------------------------------------------------------
Function Type
---------------------------------------------------------
Select this option if you need multiple lines or you have more than one dependent variable.
This option does not support control structures such as loops or if-else statements. You can however use the ternary operator.
This option provides faster performance than Origin C.
-------------------- Example1: --------------------
temp = 10;
y1 = A + exp( (x1 - xc) / temp^2 );
y2 = A + temp / (x2 - xc)^2;
-------------------- Example2: --------------------
B = A / (0.5 * (sig1+sig2) * sqrt(2*pi));
sig = ( x<xc ? sig1:sig2 );
y = y0 + B * exp(-0.5 * ((x-xc)/sig)^2);
Thanks, Snow
Dear SnowLi:
Thanks for your immediate help! It works now!
By the way, I generated too many user-defined functions, how could I delete those functions?
meilongwei |
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jasonzhao
China
262 Posts |
Posted - 04/17/2015 : 03:37:39 AM
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Hello,
You can click F9 in Origin interface to open the Fitting Function Organizer, then blowse to User Defined folder left, select the functions unwanted, click remove to delete the items.
please refer to this page for further details.
http://www.originlab.com/doc/Origin-Help/FitFunc-Organizer
Best regards!
Jason
OriginLab Technical Service
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How to write a long function for fitting?