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Initial documentation for broadcasting and general vectorization guidelines * vectorize.txi: New file. * NEWS: Update with location of broadcasting documentation. * Makefile.am: Add vectorize.texi * arith.txi: Move accumarray and accumdim docstring to vectorize.txi * container.txi: Move structfun docstring to vectorize.txi * expr.txi: Mention broadcasting where relevant. * func.txi: Move vectorize docstring to vectorize.txi * matrix.txi: Move function application section to vectorize.txi * octave.texi: Add vectorize.txi and its menu options * sparse.txi: Move spfun to vectorize.txi * tips.txi: Move and rewrite coding tips section in vectorize.txi * bsxfun.h (is_valid_bsxfun, is_valid_inplace_bsxfun): Rename warning to "Octave:broadcast" * accumdim.m: Reformat to use @example in lieu of @smallexample * warning_ids.m: Add Octave:broadcast * bsxfun.cc: Reword docstring to mention broadcasting * cellfun.cc: Move comment about efficiency from tips.txi * version.h.in: Add a big startup warning about broadcasting
author Jordi Gutiérrez Hermoso <jordigh@octave.org>
date Tue, 27 Dec 2011 15:15:41 -0500
parents b0cdd60db5e5
children 94e2a76f1e5a
comparison
equal deleted inserted replaced
14115:0b3518c1228a 14116:951eacaf9381
510 @cindex Hermitian operator 510 @cindex Hermitian operator
511 @cindex transpose, complex-conjugate 511 @cindex transpose, complex-conjugate
512 @cindex complex-conjugate transpose 512 @cindex complex-conjugate transpose
513 513
514 The following arithmetic operators are available, and work on scalars 514 The following arithmetic operators are available, and work on scalars
515 and matrices. 515 and matrices. They element-by-element operators and functions broadcast
516 (@pxref{Broadcasting}).
516 517
517 @table @asis 518 @table @asis
518 @item @var{x} + @var{y} 519 @item @var{x} + @var{y}
519 @opindex + 520 @opindex +
520 Addition. If both operands are matrices, the number of rows and columns 521 Addition. If both operands are matrices, the number of rows and columns
713 such as equality. They are written using 714 such as equality. They are written using
714 @emph{relational operators}. 715 @emph{relational operators}.
715 716
716 All of Octave's comparison operators return a value of 1 if the 717 All of Octave's comparison operators return a value of 1 if the
717 comparison is true, or 0 if it is false. For matrix values, they all 718 comparison is true, or 0 if it is false. For matrix values, they all
718 work on an element-by-element basis. For example: 719 work on an element-by-element basis. Broadcasting rules apply.
720 @xref{Broadcasting}. For example:
719 721
720 @example 722 @example
721 @group 723 @group
722 [1, 2; 3, 4] == [1, 3; 2, 4] 724 [1, 2; 3, 4] == [1, 3; 2, 4]
723 @result{} 1 0 725 @result{} 1 0
724 0 1 726 0 1
725 @end group 727 @end group
726 @end example 728 @end example
727 729
728 If one operand is a scalar and the other is a matrix, the scalar is 730 According to broadcasting rules, if one operand is a scalar and the
729 compared to each element of the matrix in turn, and the result is the 731 other is a matrix, the scalar is compared to each element of the matrix
730 same size as the matrix. 732 in turn, and the result is the same size as the matrix.
731 733
732 @table @code 734 @table @code
733 @item @var{x} < @var{y} 735 @item @var{x} < @var{y}
734 @opindex < 736 @opindex <
735 True if @var{x} is less than @var{y}. 737 True if @var{x} is less than @var{y}.
860 @opindex ! 862 @opindex !
861 Each element of the result is true if the corresponding element of 863 Each element of the result is true if the corresponding element of
862 @var{boolean} is false. 864 @var{boolean} is false.
863 @end table 865 @end table
864 866
865 For matrix operands, these operators work on an element-by-element 867 These operators work on an element-by-element basis. For example, the
866 basis. For example, the expression 868 expression
867 869
868 @example 870 @example
869 [1, 0; 0, 1] & [1, 0; 2, 3] 871 [1, 0; 0, 1] & [1, 0; 2, 3]
870 @end example 872 @end example
871 873
872 @noindent 874 @noindent
873 returns a two by two identity matrix. 875 returns a two by two identity matrix.
874 876
875 For the binary operators, the dimensions of the operands must conform if 877 For the binary operators, broadcasting rules apply. @xref{Broadcasting}.
876 both are matrices. If one of the operands is a scalar and the other a 878 In particular, if one of the operands is a scalar and the other a
877 matrix, the operator is applied to the scalar and each element of the 879 matrix, the operator is applied to the scalar and each element of the
878 matrix. 880 matrix.
879 881
880 For the binary element-by-element boolean operators, both subexpressions 882 For the binary element-by-element boolean operators, both subexpressions
881 @var{boolean1} and @var{boolean2} are evaluated before computing the 883 @var{boolean1} and @var{boolean2} are evaluated before computing the