mata_set.hlp

是一个经济学管理应用软件 很难找的 但是经济学学生又必须用到

{smcl}
{* 31mar2005}{...}
{cmd:help mata set}
{hline}
{* index mata tt}{...}
{* index set tt}{...}
{* index query tt}{...}

{title:Title}

{p 4 4 2}
{bf:[M-3] mata set -- Set and display Mata system parameters}


{title:Syntax}

{p 8 16 2}
: {cmd:mata} {cmd:query}


{p 8 16 2}
: {cmd:mata} {cmd:set} 
{cmd:matacache}{bind:   }
{it:#} [{cmd:,} {cmdab:perm:anently} ]

{p 8 16 2}
: {cmd:mata} {cmd:set} 
{cmd:matalnum}{bind:    }
{c -(}{cmd:off} | {cmd:on}{c )-}

{p 8 16 2}
: {cmd:mata} {cmd:set} 
{cmd:mataoptimize} {c -(}{cmd:on} | {cmd:off}{c )-}

{p 8 16 2}
: {cmd:mata} {cmd:set} 
{cmd:matafavor}{bind:   }
{c -(}{cmd:space} | {cmd:speed}{c )-}
[{cmd:,} {cmdab:perm:anently} ]

{p 8 16 2}
: {cmd:mata} {cmd:set} 
{cmd:matastrict}{bind:  }
{c -(}{cmd:off} | {cmd:on}{c )-}
[{cmd:,} {cmdab:perm:anently} ]

{p 8 16 2}
: {cmd:mata} {cmd:set} 
{cmd:matalibs}{bind:    }
{cmd:"}{it:libname}{cmd:;}{it:libname}{cmd:;}...{cmd:"}

{p 8 16 2}
: {cmd:mata} {cmd:set} 
{cmd:matamofirst}{bind: }
{c -(}{cmd:off} | {cmd:on}{c )-}
[{cmd:,} {cmdab:perm:anently} ]


{p 4 4 2}
These commands are for use in Mata mode following Mata's colon prompt.
To use these command from Stata's dot prompt, type

		. {cmd:mata: mata query}

		. {cmd:mata: mata set} ...


{title:Description}

{p 4 4 2}
{cmd:mata} {cmd:query} shows the values of Mata's system parameters.

{p 4 4 2}
{cmd:mata} {cmd:set} sets the value of the system parameters:

{* index matacache tt}{...}
{p 8 12 2}
{cmd:mata} {cmd:set} {cmd:matacache} specifies the maximum amount of memory, 
    in kilobytes, that may be consumed before Mata starts looking to drop
    autoloaded functions that are not currently being used.  The default value
    is 400, meaning 400 kilobytes.  This parameter affects the efficiency with
    which Stata runs.  Larger values cannot hurt, but once {cmd:matacache} is
    large enough, larger values will not improve performance.

{* index matalnum tt}{...}
{p 8 12 2}
{cmd:mata} {cmd:set} {cmd:matalnum} turns program line-number tracing on or
    off.  The default setting is off.  This setting modifies how programs are
    compiled.  Programs compiled when {cmd:matalnum} is turned on include code
    so that, if an error occurs during execution of the program, the line
    number is also reported.  Turning {cmd:matalnum} on prevents Mata from
    being able to optimize programs, so they will run more slowly.  Except
    when debugging, the recommended setting for this is off.

{* index mataoptimize tt}{...}
{* index optimization}{...}
{p 8 12 2}
{cmd:mata} {cmd:set} {cmd:mataoptimize} turns compile-time code optimization 
    on or off.  The default setting is on.  Programs compiled when
    {cmd:mataoptimize} is switched off will run more slowly and, in some cases,
    much more slowly.  The only reason to set {cmd:mataoptimize} off is if a
    bug in the optimizer is suspected.

{* index matafavor tt}{...}
{p 8 12 2}
{cmd:mata} {cmd:set} {cmd:matafavor} specifies whether, when executing code,
    Mata should favor conserving memory ({cmd:space}) or running quickly
    ({cmd:speed}).  The default setting is {cmd:space}.  Switching to
    {cmd:speed} will make Mata, in a few instances, run a little quicker
    but consume more memory.  Also see 
    {bf:{help mf_favorspeed:[M-5] favorspeed()}}.

{* index matastrict tt}{...}
{p 8 12 2}
{cmd:mata} {cmd:set} {cmd:matastrict} sets whether declarations can be 
    omitted inside the body of a program.  The default is off.  If 
    {cmd:matastrict} is switched on, compiling programs that omit the 
    declarations will result in a compile-time error;
    see {bf:{help m2_declarations:[M-2] Declarations}}.
    {cmd:matastrict} acts unexpectedly but pleasingly when set/reset inside
    ado-files; see {bf:{help m1_ado:[M-1] ado}}.
    
{* index matalibs tt}{...}
{* index .mlib library files}{...}
{p 8 12 2}
{cmd:mata} {cmd:set} {cmd:matalibs} sets the names and order of the {cmd:.mlib}
    libraries to be searched; see {bf:{help m1_how:[M-1] how -- How Mata works}}.
    {cmd:matalibs} usually is set to {cmd:"lmatabase;lmataado"}.
    However it is set, it is probably set correctly, because 
    Mata automatically searches for libraries the
    first time it is invoked in a Stata session.
    If, during a session, you erase or copy new
    libraries along the {help adopath}, the best way to reset {cmd:matalibs}
    is with the {cmd:mata mlib index} command;
    see {bf:{help mata_mlib:[M-3] mata mlib}}.
    The only reason to set {cmd:matalibs} by hand is to modify the order in
    which libraries are searched.

{* index matamofirst tt}{...}
{p 8 12 2}
{cmd:mata} {cmd:set} {cmd:matamofirst}
    states whether .mo files or .mlib libraries are searched first.  
    The default is off, meaning libraries are searched first.


{title:Option}

{p 4 8 2}
{cmd:permanently}
    specifies that, in addition to making the change right now, the
    setting be remembered and become the default setting when you
    invoke Stata in the future.


{title:Remarks}

{p 4 4 2}
Remarks are presented under the headings

	{bf:Relationship between Mata's mata set and Stata's set commands}
	{bf:c() values}


{title:Relationship between Mata's mata set and Stata's set commands}

{p 4 4 2}
The command 

	: {cmd:mata set} ...

{p 4 4 2}
issued from Mata's colon prompt and the command 

	. {cmd:set} ...

{p 4 4 2}
issued from Stata's dot prompt are the same command, so you may 
set Mata's (or even Stata's) system parameters either way.

{p 4 4 2}
The command 

	: {cmd:mata query} 

{p 4 4 2}
issued from Mata's colon prompt and the command 

	. {cmd:query mata}

{p 4 4 2}
issued from Stata's dot prompt are also the same command.


{title:c() values}

{p 4 4 2}
The following concerns Stata more than Mata.

{p 4 4 2}
Stata's c-class, {cmd:c()}, contains the values of system parameters and 
settings along with certain other constants.  {cmd:c()} values may be
referenced in Stata, either via macro substitution ({cmd:`c(current_date)'},
for example), or in expressions (in which case the macro quoting characters
may be omitted).  Stata's {cmd:c()} is also available in Mata via Mata's
{bf:{help mf_c_lc:[M-5] c()}} function.

{p 4 4 2}
Most everything set by {cmd:set} is available via {cmd:c()}, and 
Mata's set parameters are no exception:

{p 8 12 2}
{cmd:c(matacache)} returns a numeric scalar equal to the cache size

{p 8 12 2}
{cmd:c(matalnum)} returns a string equal to "{cmd:on}" or "{cmd:off}".

{p 8 12 2}
{cmd:c(mataoptimize)} returns a string equal to "{cmd:on}" or "{cmd:off}".

{p 8 12 2}
{cmd:c(matafavor)} returns a string equal to "{cmd:space}" or "{cmd:speed}".

{p 8 12 2}
{cmd:c(matastrict)} returns a string equal to "{cmd:on}" or "{cmd:off}".

{p 8 12 2}
{cmd:c(matalibs)} returns a string of library names separated by semicolons.

{p 8 12 2}
{cmd:c(matamofirst)} returns a string equal to "{cmd:on}" or "{cmd:off}".

{p 4 4 2}
The above is in Stataspeak.  Rather than referring to {cmd:c(matacache)}, 
we would refer to {cmd:c("matacache")} if we were using Mata's 
function.  The real use of these values, however, is in Stata.


{title:Also see}

{p 4 13 2}
Manual:  {hi:[M-3] mata set}

{p 4 13 2}
Online:  help for 
{bf:{help query:[R] set}},
{bf:{help creturn:[P] creturn}};
{bf:{help m3_intro:[M-3] intro}}
{p_end}