| T O P I C R E V I E W |
| vprimali |
Posted - 08/09/2005 : 03:48:12 AM
Origin Version (Select Help-->About Origin): 6.0
Operating System:xp
I want to use non-linear curve fitting for the Van Genuchten equation as Y=1/x[1+(p1*x)^p2]^p3 for water potential curve.
I did follow the help (as for new eqation) but I cannot see the simulation curve. I am wondering whether I can use this software for my purpose.
Really appreciate your help. |
| 2 L A T E S T R E P L I E S (Newest First) |
| vprimali |
Posted - 08/11/2005 : 05:30:22 AM
Hi Mike
Thanks a lot for your help. Now it works.
Primali |
| Mike |
Posted - 08/09/2005 : 09:41:14 AM
Hi vprimali:
I am going to guess that you made a small syntax error when you defined your equation. Make sure that it is entered like this ( with a "*" between the first "x" and the "(" ):
y=1/x*(1+(P1*x)^P2)^P3
On the Edit Function page of the Nonlinear Curve Fitter, set Form to Y-Script or Equations. Also, you will have to enter some initial parameter guesstimates. If you do these things, I think you'll be all set.
Mike
OriginLab
P.S. Note that my original (unedited) post used brackets "[ ]" when, in fact, I should have used parentheses "( )" -- my mistake. Origin 6/LabTalk doesn't seem to care whether parens or brackets are used but brackets wouldn't fly if defining your fitting function in Origin C. Should use "( )".
Edited by - Mike on 08/09/2005 2:13:05 PM |
