Mercurial > octave
changeset 31851:0d77475a7507 stable
doc: Expand vector indexing description (bug #63833)
expr.txi: Describe the rules for the shape of A(P)
when A and/or P are matrices, arrays, and/or vectors.
| author | Arun Giridhar <arungiridhar@gmail.com> |
|---|---|
| date | Fri, 24 Feb 2023 17:43:05 -0500 |
| parents | f184279bd67f |
| children | 2c9418209425 715c212605b7 |
| files | doc/interpreter/expr.txi |
| diffstat | 1 files changed, 12 insertions(+), 0 deletions(-) [+] |
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--- a/doc/interpreter/expr.txi Sat Feb 18 15:01:10 2023 +0100 +++ b/doc/interpreter/expr.txi Fri Feb 24 17:43:05 2023 -0500 @@ -144,6 +144,18 @@ @end group @end example +The shape rules for @var{A}(@var{P}) are: +@itemize @bullet +@item When at least one of @var{A} or @var{P} has two or more dimensions, then +@var{A}(@var{P}) takes the shape of @var{P}. This happens when at least one +of the variables is a 2-D matrix or an N-D array. + +@item When both @var{A} and @var{P} are 1-D vectors, then @var{A}(@var{P}) takes +the shape of @var{A} itself. In particular, when @var{A} is a row vector, then +@var{A}(@var{P}) is also a row vector irrespective of @var{P}'s shape. The +case when @var{A} is a column vector is analogous. +@end itemize + Note that it is permissible to use a 1-D index with a multi-dimensional object (also called linear indexing). In this case, the elements of the multi-dimensional array are taken in column-first order like Fortran. That is,