next up previous
Next: Restrictions on the Use of Sections
Up: NDF SECTIONS
Previous: The Transfer Window

Changing Dimensionality   

Now consider the case where the number of dimensions specified for a new NDF section differs from the dimensionality of the NDF from which it is derived. The NDF_ system will handle this in the same way that all dimensionality mis-matches are handled; i.e. by padding the pixel-index bounds with 1's as necessary.

For example, suppose a 1-dimensional section with shape:

(3:10)

were to be derived from a 2-dimensional NDF with shape:

(1:20, 1:20)

In this case, the 1-dimensional shape would first be padded with 1's to become:

(3:10, 1:1)

which identifies the pixels to which the new section should refer. The additional 1's will then be discarded before the section is created so that a 1-dimensional section results. A similar process would take place if the relative dimensionalities were reversed, but it would then be the original NDF's pixel-index bounds which were padded with 1's in order to identify the pixels to which the section should refer.

There are no restrictions on the creation of sections of any dimensionality up to the maximum of 7 supported by the NDF_ routines. Changes of dimensionality may also be freely combined with the selection of super-sets (see §[*]).



next up previous
Next: Restrictions on the Use of Sections
Up: NDF SECTIONS
Previous: The Transfer Window


Starlink User Note 33
R.F. Warren-Smith
11th January 2000
E-mail:rfws@star.rl.ac.uk

Copyright © 2000 Council for the Central Laboratory of the Research Councils