Simultaneous fitting to multiple data sets with multiple variables and some common parameters [duplicate]

I am trying to fit two data sets to a function model described below which share a few common parameters. Say I have two functions with some common parameter(s)

f[x_,y_]:= a*Exp[-x]*Sin[b*y] + c
g[x_,y_]:= d*Exp[-x]*Sin[b*y] + c


I generated two model data sets using a functional form similar to the ones above and tried to fit the data using NonlinearModelFit. But NonlinearModelFit fails to converge within the prescribed iterations and confidence interval.

I tried checking the threads (Combined fitting via NonlinearModelFit or http://forums.wolfram.com/mathgroup/archive/2011/Sep/msg00555.html or http://community.wolfram.com/groups/-/m/t/135933) on similar discussions but could not solve my problem. Any suggestions would be welcome.

• Could you also add the code you tried for fitting the data using NonlinearModelFit. Did you try to use good starting values for the fit? – Karsten 7. Oct 21 '14 at 4:47