Mercurial > hg > octave-lyh
changeset 6781:3058060c560f
[project @ 2007-07-19 08:07:31 by dbateman]
author | dbateman |
---|---|
date | Thu, 19 Jul 2007 08:07:32 +0000 |
parents | 38bc358b6c9a |
children | e3f06290847c |
files | doc/ChangeLog doc/interpreter/bit.txi doc/interpreter/numbers.txi doc/interpreter/octave.texi scripts/ChangeLog scripts/plot/fplot.m |
diffstat | 6 files changed, 156 insertions(+), 39 deletions(-) [+] |
line wrap: on
line diff
--- a/doc/ChangeLog +++ b/doc/ChangeLog @@ -1,3 +1,10 @@ +2007-07-19 David Bateman <dbateman@free.fr> + + * interpreter/bit.xi: Remove. + * interpreter/numbers.txi: Move here, and add examples. + * interpreter/octave.texi: Remove "Bit manipulation" chapter and make + it a sub-section of the "Numeric Data Types" chapter. + 2007-07-06 David Bateman <dbateman@free.fr> * interpreter/arith.txi: Add accumarray.
deleted file mode 100644 --- a/doc/interpreter/bit.txi +++ /dev/null @@ -1,24 +0,0 @@ -@c Copyright (C) 2007 John W. Eaton -@c This is part of the Octave manual. -@c For copying conditions, see the file gpl.texi. - -@node Bit Manipulations -@chapter Bit Manipulations - -Octave provides the following functions for bit twiddling. - -@DOCSTRING(bitset) - -@DOCSTRING(bitget) - -@DOCSTRING(bitcmp) - -@DOCSTRING(bitshift) - -@DOCSTRING(bitand) - -@DOCSTRING(bitor) - -@DOCSTRING(bitxor) - -@DOCSTRING(bitmax)
--- a/doc/interpreter/numbers.txi +++ b/doc/interpreter/numbers.txi @@ -78,6 +78,7 @@ * Matrices:: * Ranges:: * Integer Data Types:: +* Bit Manipulations:: * Logical Values:: * Predicates for Numeric Objects:: @end menu @@ -467,6 +468,87 @@ result is often floored to the nearest integer. So, the result of @code{int32(5)./int32(8)} is @code{1}. +@node Bit Manipulations +@section Bit Manipulations + +Octave provides a number of functions for the manipulation of numeric +values on a bit by bit basis. The basic functions to set and obtain the +values of individual bits are @code{bitset} and @code{bitget}. + +@DOCSTRING(bitset) + +@DOCSTRING(bitget) + +The arguments to all of Octave's bitwise operations can be scalar or +arrays, except for @code{bitcmp}, whose @var{k} argument must a +scalar. In the case where more than one argument is an array, then all +arguments must have the same shape, and the bitwise operator is applied +to each of the elements of the argument individually. If at least one +argument is a scalar and one an array, then the scalar argument is +duplicated. Therefore + +@example +bitget (100, 8:-1:1) +@end example + +is the same as + +@example +bitget (100 * ones (1, 8), 8:-1:1) +@end example + +It should be noted that all values passed to the bit manipulation +functions of Octave are treated as integers. Therefore, even though the +example for @code{bitset} above passes the floating point value +@code{10}, it is treated as the bits @code{[1, 0, 1, 0]} rather than the +bits of the native floating point format representation of @code{10}. + +As the maximum number that can be represented by a number is important +for bit manipulation, particularly when forming masks, Octave supplies +the function @code{bitmax}. + +@DOCSTRING(bitmax) + +This is the double precision version of the functions @code{intmax}, +previously discussed. + +Octave also include the basic bitwise 'and', 'or' and 'exclusive or' +operators. + +@DOCSTRING(bitand) + +@DOCSTRING(bitor) + +@DOCSTRING(bitxor) + +The bitwise 'not' operator is unary operator that performs a logial +negation of each of the bits of the value. For this to make sense, the +mask against which the value is negated must be defined. Octave's +bitwise 'not' operator is @code{bitcmp}. + +@DOCSTRING(bitcmp) + +Octave also includes the ability to left and right values bitwise. + +@DOCSTRING(bitshift) + +Bits that are shifted out of either end of the value are lost. Octave +also uses arithmetic shifts, where the sign bit of the value is keep +during a right shift. For example + +@example +@group +bitshift (-10, -1) +@result{} -5 +bitshift (int8 (-1), -1) +@result{} -1 +@end group +@end example + +Note that @code{bitshift (int8 (-1), -1)} is @code{-1} since the bit +representation of @code{-1} in the @code{int8} data type is @code{[1, 1, +1, 1, 1, 1, 1, 1]}. + @node Logical Values @section Logical Values
--- a/doc/interpreter/octave.texi +++ b/doc/interpreter/octave.texi @@ -145,7 +145,6 @@ * Plotting:: * Matrix Manipulation:: * Arithmetic:: -* Bit Manipulations:: * Linear Algebra:: * Nonlinear Equations:: * Sparse Matrices:: @@ -250,6 +249,7 @@ * Matrices:: * Ranges:: * Integer Data Types:: +* Bit Manipulations:: * Logical Values:: * Predicates for Numeric Objects:: @@ -584,7 +584,6 @@ @include plot.texi @include matrix.texi @include arith.texi -@include bit.texi @include linalg.texi @include nonlin.texi @include sparse.texi
--- a/scripts/ChangeLog +++ b/scripts/ChangeLog @@ -1,3 +1,7 @@ +2007-07-19 David Bateman <dbateman@free.fr> + + * plot/fplot.m: More compatible version. + 2007-07-18 Michael Goffioul <michael.goffioul@gmail.com> * plot/clf.m: Check for valid handle before deleting.
--- a/scripts/plot/fplot.m +++ b/scripts/plot/fplot.m @@ -19,50 +19,99 @@ ## -*- texinfo -*- ## @deftypefn {Function File} {} fplot (@var{fn}, @var{limits}) +## @deftypefnx {Function File} {} fplot (@var{fn}, @var{limits}, @var{tol}) ## @deftypefnx {Function File} {} fplot (@var{fn}, @var{limits}, @var{n}) +## @deftypefnx {Function File} {} fplot (@dots{}, @var{LineSpec}) ## Plot a function @var{fn}, within the defined limits. @var{fn} ## an be either a string, a function handle or an inline function. ## The limits of the plot are given by @var{limits} of the form ## @code{[@var{xlo}, @var{xhi}]} or @code{[@var{xlo}, @var{xhi}, -## @var{ylo}, @var{yhi}]}. @var{n} is the number of points to use and -## defaults to 100. +## @var{ylo}, @var{yhi}]}. @var{tol} is the default tolerance to use for the +## plot, and if @var{tol} is an integer it is assumed that it defines the +## number points to use in the plot. The @var{LineSpec} is passed to the plot +## command. ## ## @example ## fplot ("cos", [0, 2*pi]) ## fplot ("[cos(x), sin(x)]", [0, 2*pi]) ## @end example +## @seealso{plot} ## @end deftypefn -function fplot (fn, limits, n) +function fplot (fn, limits, n, linespec) if (nargin < 2 || nargin > 3) print_usage (); endif if (nargin < 3) - n = 100; + n = 0.002; endif - x = linspace (limits(1), limits(2), n)'; + have_linespec = true; + if (nargin < 4) + have_linespec = false; + endif - nam = fn; + if (ischar (n)) + have_linespec = true; + linespec = n; + n = 0.002; + endif + if (strcmp (typeinfo (fn), "inline function")) fn = vectorize (fn); - y = fn (x); nam = formula (fn); elseif (isa (fn, "function_handle")) - y = fn (x); nam = func2str (fn); elseif (all (isalnum (fn))) - y = feval (fn, x); + nam = fn; else - finl = vectorize (inline (fn)); - y = finl (x); + fn = vectorize (inline (fn)); + nam = formula (fn); + endif + + if (floor(n) != n) + tol = n; + x0 = linspace (limits(1), limits(2), 3)'; + y0 = feval (fn, x0); + err0 = Inf; + n = 5; + x = linspace (limits(1), limits(2), n)'; + y = feval (fn, x); + + while (n < 2 .^ 20) + y00 = interp1 (x0, y0, x, "linear"); + err = 0.5 * max (abs ((y00 - y) ./ (y00 + y))(:)); + if (err == err0 || 0.5 * max (abs ((y00 - y) ./ (y00 + y))(:)) < tol) + break; + endif + x0 = x; + y0 = y; + err0 = err; + n = 2 * (n - 1) + 1; + x = linspace (limits(1), limits(2), n)'; + y = feval (fn, x); + endwhile + else + x = linspace (limits(1), limits(2), n)'; + y = feval (fn, x); endif if (length (limits) > 2) axis (limits); endif - plot (x, y, [";", nam, ";"]); - + if (have_linespec) + plot (x, y, linespec); + else + plot (x, y); + endif + if (isvector(y)) + legend (nam); + else + for i=1:columns(y) + nams{i} = sprintf ("%s(:,%i)", nam, i); + endfor + legend (nams{:}); + endif endfunction