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sevny
USA
5 Posts |
 Posted - 02/01/2013 : 10:37:30 PM
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Origin Ver. and Service Release (Select Help-->About Origin): Origin 9.0
Operating System:Windows
OK, here is the problem I am running into, simply, I am trying nonlinear curve fitting using multiple equations with intermediate variables. It worked well for the simple ones, but when quadratic or higher order equations are present, I have the problem of how to select the correct root out of the multiple roots. The equations are as follows.
In the following equations, x is independent, y is dependent; H and Ka are parameters; L0,P0,R0,V0,Vi and fi are constants; L1, L2, P1 and P2 are intermediate variables, L1 or L2 are greater than zero, smaller than L0; P1 and P2 are greater than zero, smaller than P0. When solve the equations, two L1 and two L2 will be generated from the quadratic equation, so the difficulty is how to realize root selection here. Thank you very much for your time. Any advice or comment are appreciated.
L1=L0*(1-R0/(R0+x))/(1+Ka*P1);
P1=P0*R0/((R0+x)*(1+Ka*L1));
L2=L0*(1-R0/((R0+x)*fi))/(1+Ka*P2);
P2=P0*R0/((R0+x)*fi*(1+Ka*L1));
y=V0*H*Ka*(P1*L1-P2*L2*fi)/(Vi*L0);
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cc261
22 Posts |
Posted - 02/04/2013 : 10:03:21 PM
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| put out all relative knowing data, I may try for you! |
Edited by - cc261 on 02/04/2013 10:04:24 PM |
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sevny
USA
5 Posts |
Posted - 02/04/2013 : 10:55:05 PM
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Thank you so much.
Hu Qi |
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Curve fitting with intermediate variables