# ICONICO

## UltimaCalc

### UltimaCalc Posted in the UltimaCalc Forum.

## Fit a nonlinear equation to data

I am looking for info regarding... Fit a nonlinear (or any equation for that matter) equation to data.. and I am not finding information on this subject.

JB

## Fit a nonlinear equation to data

Hi JB

Please take a look at the "Regression and Least Squares Fit" module. He have a write up of it here:

http://www.iconico.com/ul...ssion.aspx

There is also more details on this in the application's help file.

To summarize:

To call up the Regression window, select the menu item File = Regression / Least Squares.

Five modes of regression / least squares calculation are supported. All except 'Absolute Deviation' attempt to minimize the sum of the squares of the differences between each (X, Y) data point and the 'predicted' Y value.

1) Linear regression fits a linear function, i.e. a straight line, to the data.

2) Polynomial regression attempts to fit a polynomial of specified order to the data.

3) Non-linear least squares fit attempts to fit an arbitrary expression to the data, adjusting the expression's variables for the best match.

4) Multivariate regression attempts to fit a linear function of a set of variates X0, X1, X2 etc.

5) Absolute deviation regression is similar to linear regression, but minimises the sum of the absolute deviations (rather than the sum of their squares) to reduce the effects of outlying points.

## Fit a nonlinear equation to data

Thank you. Knew there wasn't an obvious answer I thought perhaps a little bit more of a walk-through. But your answer helps.
TX
JB

## Fit a nonlinear equation to data

Glad to hear it, please check the help file too. If you have questions we're happy to help.
by Nico Westerdale on Jun 11 2009 11:31am Reply