# POWFIT

## Purpose:

Fits y(x) = A xb using linearization.

## Syntax:

POWFIT(series)

(fit, coef) = POWFIT(series)

(fit, A, b) = POWFIT(series)

 series - Input series or array.

## Returns:

A series.

(fit, coef) = POWFIT(series) returns both the fit and the coefficients as a series.

(fit, A, b) = POWFIT(series) returns both the fit as a series and the coefficients as separate coefficients.

## Example:

W1: 10 * (1..100)^0.5

W2: powfit(w1);overp(w1, lred)

overplots the original data with the calculated power fit.

## Example:

(fit, coef) = powfit(w1)

fit is the same series as in W2

coef == {10.0, 0.5}.

## Remarks:

POWFIT fits a power curve of the form:

The fit is accomplished by fitting a line to the following equation:

If x or y are not positive, the result will be complex.

The fitted power curve (fit, coef) = powfit(series) returns both the fit and the coefficients as a series where coef is in the form {A, b}.

The fitted power curve (fit, A, b) = powfit(series) returns the fit as a series and the coefficients as separate scalars.