## Changes Introduced in V1.3

The following describes the most significant changes which occurred in the AST library between versions V1.2 and V1.3 (not the most recent version):

1. A new set of functions, astResample1#1X2#2astResample1#1X2#2, has been introduced to provide efficient resampling of gridded data, such as spectra and images, under the control of a geometrical transformation specified by a MappingMapping. A variety of sub-pixel interpolation schemes are supported.

2. A new class, PcdMapPcdMap, has been introduced. This is a specialised form of Mapping which implements 2-dimensional pincushion or barrel distortion.

3. A bug has been fixed which could cause a FitsChanFitsChan to produce too many digits when formatting floating point values for inclusion in a FITS header if the numerical value was in the range -0.00099999...to -0.0001.

4. A bug has been fixed which could cause a FitsChan to lose the comment associated with a string value in a FITS header.

5. A FitsChan now reports an error if it reads a FITS header which identifies a non-standard sky projection (previously, this was accepted without error and a Cartesian projection used instead).

6. A bug has been fixed which could prevent conversion between the coordinate systems represented by two CmpFrames. This could only occur if the CmpFrames contained a relatively large number of nested Frames.

7. Further improvements have been made to the simplification of compound Mappings, including fixes for several bugs which could cause indefinite looping or unwanted error messages.

8. Some memory leaks have been fixed.

9. A small number of documentation errors have been corrected.