I have a modeled data set R_mod which is a dependent on 5 other variables. Individual relationship of R_mod with 5 independent variables are polynomial relationships. Now i want to fit measured data R_mea with modeled data R_mod by adjusting 5 independent variables. Please suggest me how can perform this...i have another question as there will be infinite number of solutions to this problem how can i pick the reasonable solution.....thanks in advance...

Many things to think about... I suppose you could try linear regression, extract the coefficients, and compare them to what your model produces. 
http://www.mathworks.com/access/helpdesk/help/techdoc/data_analysis/f1-8450.html
You should check that the predictors aren't correlated, otherwise your coefficients will be junk (/www.graphpad.com/articles/Multicollinearity.htm)