Mercurial > hg > octave-nkf
changeset 6554:5dde4dc2bcaf
[project @ 2007-04-20 17:16:50 by jwe]
author | jwe |
---|---|
date | Fri, 20 Apr 2007 17:16:50 +0000 |
parents | af5025cb0f2b |
children | 69e864d21c11 |
files | doc/interpreter/func.txi doc/interpreter/octave.texi doc/interpreter/strings.txi |
diffstat | 3 files changed, 149 insertions(+), 61 deletions(-) [+] |
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--- a/doc/interpreter/func.txi +++ b/doc/interpreter/func.txi @@ -553,26 +553,25 @@ When Octave encounters an identifier that is undefined, it first looks for variables or functions that are already compiled and currently listed in its symbol table. If it fails to find a definition there, it -searches the list of directories specified by the internal variable -@code{LOADPATH} for files ending in @file{.m} that have the same base -name as the undefined identifier.@footnote{The @samp{.m} suffix was -chosen for compatibility with @sc{Matlab}.} Once Octave finds a file -with a name that matches, the contents of the file are read. If it -defines a @emph{single} function, it is compiled and executed. -@xref{Script Files}, for more information about how you can define more -than one function in a single file. +searches a list of directories (the @deffn{path}) for files ending in +@file{.m} that have the same base name as the undefined +identifier.@footnote{The @samp{.m} suffix was chosen for compatibility +with @sc{Matlab}.} Once Octave finds a file with a name that matches, +the contents of the file are read. If it defines a @emph{single} +function, it is compiled and executed. @xref{Script Files}, for more +information about how you can define more than one function in a single +file. When Octave defines a function from a function file, it saves the full -name of the file it read and the time stamp on the file. After -that, it checks the time stamp on the file every time it needs the -function. If the time stamp indicates that the file has changed since -the last time it was read, Octave reads it again. +name of the file it read and the time stamp on the file. If the time +stamp on the file changes, Octave may reload the file. When Octave is +running interactively, time stamp checking normally happens at most once +each time Octave prints the prompt. Searching for new function +definitions also occurs if the current working directory changes. Checking the time stamp allows you to edit the definition of a function while Octave is running, and automatically use the new function -definition without having to restart your Octave session. Checking the -time stamp every time a function is used is rather inefficient, but it -has to be done to ensure that the correct function definition is used. +definition without having to restart your Octave session. To avoid degrading performance unnecessarily by checking the time stamps on functions that are not likely to change, Octave assumes that function @@ -584,11 +583,10 @@ function files that are distributed with Octave. If you know that your own function files will not change while you are -running Octave, you can improve performance by setting the variable -@code{ignore_function_time_stamp} to @code{"all"}, so that Octave will -ignore the time stamps for all function files. Setting it to -@code{"system"} gives the default behavior. If you set it to anything -else, Octave will check the time stamps on all function files. +running Octave, you can improve performance by calling +@code{ignore_function_time_stamp ("all")}, so that Octave will +ignore the time stamps for all function files. Passing +@code{"system"} to this function resets the default behavior. @c FIXME -- note about time stamps on files in NFS environments? @@ -917,28 +915,7 @@ Additional examples for writing dynamically linked functions are available in the files in the @file{src} directory of the Octave -distribution. Currently, this includes the files - -@example -@group -balance.cc fft2.cc inv.cc qzval.cc -chol.cc filter.cc log.cc schur.cc -colloc.cc find.cc lsode.cc sort.cc -dassl.cc fsolve.cc lu.cc svd.cc -det.cc givens.cc minmax.cc syl.cc -eig.cc hess.cc pinv.cc -expm.cc ifft.cc qr.cc -fft.cc ifft2.cc quad.cc -@end group -@end example - -@noindent -These files use the macro @code{DEFUN_DLD_BUILTIN} instead of -@code{DEFUN_DLD}. The difference between these two macros is just that -@code{DEFUN_DLD_BUILTIN} can define a built-in function that is not -dynamically loaded if the operating system does not support dynamic -linking. To define your own dynamically linked functions you should use -@code{DEFUN_DLD}. +distribution. There is currently no detailed description of all the functions that you can call in a built-in function. For the time being, you will have to @@ -960,18 +937,107 @@ @menu * Function Handles:: +* Anonymous Functions:: * Inline Functions:: @end menu @node Function Handles @subsection Function Handles +A function handle is a pointer to another function and is defined with +the syntax + +@example +@@@var{function-name} +@end example + +@noindent +For example + +@example +f = @sin; +@end example + +@noindent +Creates a function handle called @code{f} that refers to the the +function @code{sin}. + +Function handles are used to call other functions indirectly, or to pass +a function as an argument to another function like @code{quad} or +@code{fsolve}. For example + +@example +f = @sin; +quad (f, 0, pi) + @result 1.8391 +@end example + +You may use @code{feval} to call a function using function handle, or +simply write the name of the function handle follwed by an argument +list. If there are no arguments, you must use an empty argument list +@samp{()}. For example + +@example +f = @sin; +feval (f, pi/4) + @result 0.70711 +f (pi/4) + @result 0.70711 +@end example + @DOCSTRING(functions) @DOCSTRING(func2str) @DOCSTRING(str2func) +@node Anonymous Functions:: +@subsection Anonymous Functions + +Anonymous functions are defined using the syntax + +@example +@@(@var{argument-list}) @var{expression} +@end example + +@noindent +Any variables that are not found in the argument list are inherited from +the enclosing scope. Anonymous functions are useful for creating simple +unnamed functions from expressions or for wrapping calls to other +functions to adapt them for use by functions like @code{quad}. For +example, + +@example +f = @@(x) x.^2; +quad (f, 0, 10) + @result 333.33 +@end example + +@noindent +creates a simple unnamed function from the expression @code{x.^2} and +passes it to @code{quad}, + +@example +quad (@@(x) sin (x), 0, pi) + @result 1.8391 +@end example + +@noindent +wraps another function, and + +@example +a = 1; +b = 2; +quad (@@(x) betainc (x, a, b), 0, 0.4) + @result 1.3867 +@end example + +@noindent +adapts a function with several parameters to the form required by +@code{quad}. In this example, the values of @var{a} and @var{b} that +are passed to @code{betainc} are inherited from the current +environment. + @node Inline Functions @subsection Inline Functions @@ -1019,6 +1085,10 @@ @item elfun Elementary functions. +@item finance +Functions for computing interest payments, investment values, and rates +of return. + @item general Miscellaneous matrix manipulations, like @code{flipud}, @code{rot90}, and @code{triu}, as well as other basic functions, like @@ -1036,6 +1106,15 @@ @item miscellaneous Functions that don't really belong anywhere else. +@item optimization +Minimization of functions. + +@item path +Functions to manage the directory path Octave uses to find functions. + +@item pkg +Install external packages of functions in Octave. + @item plot A set of functions that implement the @sc{Matlab}-like plotting functions. @@ -1048,6 +1127,9 @@ @item signal Functions for signal processing applications. +@item sparse +Functions for handling sparse matrices. + @item specfun Special functions. @@ -1063,6 +1145,9 @@ @item strings Miscellaneous string-handling functions. +@item testfun +Perform unit tests on other functions. + @item time Functions related to time keeping. @end table
--- a/doc/interpreter/octave.texi +++ b/doc/interpreter/octave.texi @@ -346,7 +346,7 @@ * Output Conversion Syntax:: * Table of Output Conversions:: * Integer Conversions:: -* Floating-Point Conversions:: Other Output Conversions:: +* Floating-Point Conversions:: * Other Output Conversions:: * Formatted Input:: * Input Conversion Syntax::
--- a/doc/interpreter/strings.txi +++ b/doc/interpreter/strings.txi @@ -28,27 +28,30 @@ (@pxref{Arithmetic Ops}) but double-quote marks have no other purpose in Octave, it is best to use double-quote marks to denote strings. -@c FIXME -- this is probably pretty confusing. +@cindex escape sequence notation +In double-quoted strings, the backslash character is used to introduce +@deffn{escape sequences} that reresent other characters. For example, +@samp{\n} embeds a newline character in a double-quoted string and +@samp{\"} embeds a double quote character. -@cindex escape sequence notation -Some characters cannot be included literally in a string constant. You -represent them instead with @dfn{escape sequences}, which are character -sequences beginning with a backslash (@samp{\}). +In single-quoted strings, backslash is not a special character. + +Here is an example showing the difference -One use of an escape sequence is to include a double-quote -(single-quote) character in a string constant that has been defined -using double-quote (single-quote) marks. Since a plain double-quote -would end the string, you must use @samp{\"} to represent a single -double-quote character as a part of the string. The backslash character -itself is another character that cannot be included normally. You must -write @samp{\\} to put one backslash in the string. Thus, the string -whose contents are the two characters @samp{"\} may be written -@code{"\"\\"} or @code{'"\\'}. Similarly, the string whose contents are -the two characters @samp{'\} may be written @code{'\'\\'} or @code{"'\\"}. +@example +toascii ("\n") + @result 10 +toascii ('\n') + @result [ 92 110 ] +@end example -Another use of backslash is to represent unprintable characters -such as newline. While there is nothing to stop you from writing most -of these characters directly in a string constant, they may look ugly. +You may also insert a single quote character in a single-quoted string +by using two single quote characters in succession. For example, + +@example +'I can''t escape' + @result I can't escape +@end example Here is a table of all the escape sequences used in Octave. They are the same as those used in the C programming language.