Concurrent Curve Fitting... II

*To*: mathgroup at smc.vnet.net*Subject*: [mg18624] Concurrent Curve Fitting... II*From*: "Robert Carneim" <rdc120 at psu.edu>*Date*: Tue, 13 Jul 1999 01:01:40 -0400*Organization*: PSU PMC*Sender*: owner-wri-mathgroup at wolfram.com

First of all, thank you for your numerous replies... I'm still working my way through them all... Secondly, there was some confusion as to whether the xn and yn parameters were known already or not... they are not: m and b are unknown and common to both sets, x1 and y1 are unknown parameters for set 1, and x2 and y2 are unknown parameters for set 2. Also, this particular example can be reduced to the unknowns m (common) and b1=b+y1-m*x2 (set 1) and b2=b+y2-m*x2 (set 2); I just left it in the expanded form for clarity. Thanks again, -rdc ---- original message: Can anyone help me? Here's what I want to do: I have two sets of data which are related in such a way that, when plotted, they should have the same shape (or I want to force the curve fits to have the same shape), but at a different location. So, for example (and simplicity} suppose I have two sets of data which can be fit by lines, y=mx+b. I want to fit data set 1 to (y-y1)=m(x-x1)+b, and data set 2 to (y-y2)=m(x-x2)+b, where m and b are common and xn and yn are specific to the data set. This is a fairly easy to do indirectly, even by hand, but is there a way to get Mathematica to do this directly, i.e., finding the two curve fits concurrently? Obviously, I'm trying to do this for much more complex models. Any input would be appreciated. Thanks, -rdc.