Origin Ver. and Service Release (Select Help-->About Origin): OriginPro 9
Operating System: windows vista
Hi,
I am trying to fit my data with a set of equations. The equations are as follows,
G=R0/(R0+x);
M1=M0*G/(1+Ka*A1+Kb*B1+c*Ka*Kb*A1*B1);
M2=M0*G/(f*(1+Ka*A2+Kb*B2+c*Ka*Kb*A2*B2));
A1=A0*(1-G)/(1+Ka*M1+c*Ka*Kb*M1*B1);
A2=A0*(1-G/f)/(1+Ka*M2+c*Ka*Kb*M2*B2);
B1=B0*(1-G)/(1+Kb*M1+c*Ka*Kb*A1*M1);
B2=A0*(1-G/f)/(1+Kb*M2+c*Ka*Kb*A2*M2);
y=V0*(Ha*Ka*(M1*A1-M2*A2*f)+Hb*Kb*(M1*B1-M2*B2*f)+(Ha+Hb+h)*c*Ka*Kb*(M1*A1*B1-M2*A2*B2*f))/(Vi*A0);
in which x is independent,y is dependent; Ka,Kb,Ha,Hb,h and c are parameters to be derived; V0,Vi,A0,B0,M0,f and R0 are constants; M1,M2,A1,A2,B1,B2 are intermediate variables. All the intermediate variables shouble be greater than zero. While trying to fit with the equations, I realized that these intermediate variables obtained by solving the equations have multiple roots, although only those greater than zero are correct and shouble be used for calculating y. Therefore, my question is how I can select the correct roots from the multiple solutions and submit to calculation of y. Alternatively,
is there any other way to do the fitting with the equation set? Thank you very much for any advice or comments.
Hu Qi |
Curve fitting with intermediate variables
Posted - 02/01/2013 : 4:27:38 PM
