## NAME

samplepars -- Edit parameters related to data sampling and rejection.

## USAGE

`samplepars`

## DESCRIPTION

The points to be fit are determined by selecting a sample of data
specified by the parameter `sample` and taking either the average or
median of the number of points specified by the parameter `naverage`.
The type of averaging is selected by the sign of the parameter and the
number of points is selected by the absolute value of the parameter.

If `niterate` is greater than zero the sigma of the residuals between the
fitted points and the fitted function is computed and those points whose
residuals are less than LOW_REJECT * sigma or HIGH_REJECT * sigma value
are excluded from the fit. Points within a distance of `grow` pixels of a
rejected pixel are also excluded from the fit. The function is then
refit without the rejected points. The rejection can be iterated the
number of times specified by the parameter `niterate`. Note a rejection
value of zero is the same as no rejection.

## PARAMETERS

- (axis = 1) [integer, min=1, max=INDEF]
- Axis onto which to project if fitting an image section of more than one
dimension. It is relative to the full image, and not to the particular
section being fitted. For instance, when fitting the section
data[100:*:*],
`axis`can have either a value of 2 or 3. Notice that redundant section constructs such as dev$pix[256:256,*] will not work.

- (sample = *) [string]
- Sample points to use in fit. The default (*) is to set the sample to the full data range. Sub-ranges may be specified by two real numbers separated by a colon. Any number of sub-ranges are allowed, separated by commas or spaces. The numbers must be in the same units as the X-axis.

- (naverage = 1) [integer]
- Number of points to be used in sample averaging.

- (low_reject = 0.) [real, min=0., max=INDEF]
- Lower threshold (in sigma) of the fit. Values below this level will be rejected.

- (high_reject = 0.) [real, min=0., max=INDEF]
- Upper threshold (in sigma) of the fit. Values above this level will be rejected.

- (niterate = 1) [integer, min=0, max=INDEF]
- Number of rejection iterations.

- (grow = 0.) [real, min=0., max=INDEF]
- Rejection growing radius (in pixels).