The routine sets new pixel-index bounds for an NDF (or NDF section). The number of NDF dimensions may also be changed. If a base NDF is specified, then a permanent change is made to the actual data object and this will be apparent through any other NDF identifiers which refer to it. However, if an identifier for an NDF section is specified, then its bounds are altered without affecting other identifiers.

CALL NDF_SBND( NDIM, LBND, UBND, INDF, STATUS )

NDIM = INTEGER (Given)

LBND( NDIM ) = INTEGER (Given)

UBND( NDIM ) = INTEGER (Given)

INDF = INTEGER (Given)

STATUS = INTEGER (Given and Returned)

• The bounds of an NDF section cannot be altered while any of its array components (or any of its axis arrays) is mapped for access through the identifier supplied to this routine.

• The bounds of a base NDF cannot be altered while any part of any of its array components (or any of its axis arrays) is mapped for access, even through another identifier.

• The pixel values of any defined NDF array component will be retained if those pixels lie within both the old and new bounds. Any pixels lying outside the new bounds will be lost and cannot later be recovered by further changes to the NDF’s bounds. Any new pixels introduced where the new bounds extend beyond the old ones will be assigned the "bad" value, and subsequent enquiries about the presence of bad pixels will reflect this.

• If the new NDF bounds extend beyond the bounds of the associated base NDF and any of the NDF’s axis arrays have defined values, then these values will be extrapolated as necessary.

• If the bounds of a base NDF are to be altered and retention of the pixel values of any of its components is not required, then a call to NDF_RESET should be made before calling this routine. This will eliminate any unnecessary processing which might be needed to retain the existing values. This step is not necessary with an NDF section, as no processing of pixel values takes place in this case.