Hello,
Which version of LabVIEW are you using? LabVIEW 8.0 has a fitting palette under the Mathematics palette - that's the first place to go looking for fitting functions. The LabVIEW Help has details of each function, including links to examples (or just see the example finder). You may be interested in the Non-Linear Curve Fit VI (it uses the Lev-Mar algorithm), and specifically looking at the "Fit sum of 3 gaussians with offset.vi" in the example finder (click the link to the example from the LabVIEW help for that function - clicking the link in the context help for that function is fast way to get to the LabVIEW help for that function). Since the gaussian is an expontential function, and the example sums 3 with an offset as the model function, it is similar to what you would like to do, and should serve as a good example/model for your implementation.
Thank you,
JLS
