### SQORST

Squashes or stretches an NDF

#### Description:

An output NDF  is produced by squashing or stretching an input NDF along one or more of its dimensions. The shape of the output NDF can be specified in one of two ways, according to the value of the MODE parameter; either a distortion factor is given for each dimension, or its lower and upper pixel bounds are given explicitly.

#### Usage:

sqorst in out $\left\{\right\$
factors lbound=? ubound=? pixscale=?

mode

#### Parameters:

Assigning a value to this parameter indicates that a single axis should be squashed or stretched. If a null (!) value is supplied for AXIS, a squash or stretch factor must be supplied for each axis in the manner indicated by the MODE parameter. If a non-null value is supplied for AXIS, it should be the integer index of the axis to be squashed or stretched (the first axis has index 1). In this case, only a single squash or stretch factor should be supplied, and all other axes will be left unchanged. If MODE is set to PixelScale", then the supplied value should be the index of a WCS axis. Otherwise it should be the index of a pixel axis. [!]
Determines the centre about which the WCS co-ordinates are stretching or squashing. The following values are permitted.
• "Centre" –- The WCS co-ordinates at the centre of the output NDF are the same as those at the centre of the input NDF.

• "Origin" –- The WCS co-ordinates at the pixel origin of the output NDF are the same as those at the pixel origin of the input NDF.

["Centre"]

If set TRUE, then the output pixel values will be scaled in such a way as to preserve the total data value in a feature on the sky. The scaling factor is the ratio of the output pixel size to the input pixel size. This ratio is evaluated once for each panel of a piece-wise linear approximation to the Mapping, and is assumed to be constant for all output pixels in the panel. [FALSE]
##### FACTORS( ) = _DOUBLE (Read)
This parameter is used only if MODE="Factors". It defines the factor by which each dimension will be distorted to produce the output NDF. A factor greater than one is a stretch and less than one is a squash. If no value has been supplied for Parameter AXIS, the number of values supplied for FACTORS must be the same as the number of pixel axes in the NDF. If a non-null value has been supplied for Parameter AXIS, then only a single value should be supplied for FACTORS and that value will be used to distort the axis indicated by Parameter AXIS.
This parameter is only used if MODE="Bounds". It specifies the lower pixel-index values of the output NDF. If no value has been supplied for Parameter AXIS, the number of values supplied for LBOUND must be the same as the number of pixel axes in the NDF. If a non-null value has been supplied for Parameter AXIS, then only a single value should be supplied for LBOUND and the supplied value will be used as the new lower bounds on the axis indicated by Parameter AXIS. If null (!) is given, the lower pixel bounds of the input NDF will be used.
• "Auto" –- Equivalent to "BlockAve" with an appropriate PARAMS for squashes by a factor of 2 or more, otherwise equivalent to "Linear".
• "Nearest" –- Nearest-neighbour sampling.
• "Linear" –- Linear interpolation.
• "Sinc" –- Sum of surrounding pixels weighted using a one-dimensional