(adsbygoogle = window.adsbygoogle || []).push({}); "Shape preserving" fitting algorithms

Does anyone know if there is such a thing as a "shape preserving" fitting algorithm?

Now and then I run into the following problem: I have a set of rapidly varying data and try to fit it using an equation with e.g. 5 unknowns; I know that I can make it fit "by hand" (basically trial and error). However, when I try to fit it I often get that the solution is e.g. a straight line through the data; simply because it is a "good" solution in the least-square sense(although it doesn't make much sense from physical point of view). The wiki on the MLA even shows one example of this.

I can obviously get it to fit if I start with a "good" guess but that sort of defies the purpose of automatic fitting (and I often need to fit hundreds of experimental curves and sometimes in "real time" so doing it by hand is not really an option).

I understand that the problem is -there are several minima and the fitting algorithms finds the "wrong one" unless the initial conditions are close to the real solution- but I don't know how to solve it.

Presumably this is well-known problem, but I haven't been able to find a reference where they discuss possible solutions.

Is there any way of adding "shape preservation" to e.g. the MLA? E.g. by somehow adding that the condition for a "best fit" is that also the derivatives fit reasonably well?

Or are there any other possible solutions?

**Physics Forums - The Fusion of Science and Community**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Shape preserving fitting algorithms

Loading...

Similar Threads - Shape preserving fitting | Date |
---|---|

B What is the name of this triangular geometric shape? | Feb 20, 2018 |

B Rectangular Prism out of different shapes? | Feb 23, 2017 |

I What shape is the ecliptic as seen from Earth? | Sep 30, 2016 |

I What do you call a parallelepiped that isn't a cube? | Aug 16, 2016 |

I Why a bijective map may not preserve area? | Jul 11, 2016 |

**Physics Forums - The Fusion of Science and Community**