functions.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}
{* 03mar2005}{...}
{cmd:help functions}
{hline}

{title:Title}

{p2colset 5 22 24 2}{...}
{p2col :{hi:[D] functions} {hline 2}}Functions in expressions{p_end}
{p2colreset}{...}

    Quick references are available for the following types of functions:

    {c TLC}{hline 38}{c TT}{hline 25}{c TRC}
    {c |} Type of function{space 21}{c |} See help                {c |}
    {c LT}{hline 38}{c +}{hline 25}{c RT}
    {c |} Mathematical functions{space 15}{c |} {help math functions}          {c |}
    {c |} Probability distributions and        {c |}                         {c |}
    {c |}   density functions{space 18}{c |} {help density functions}       {c |}
    {c |} Random-number functions{space 14}{c |} {help random-number functions} {c |}
    {c |} String functions{space 21}{c |} {help string functions}        {c |}
    {c |} Programming functions{space 16}{c |} {help programming functions}   {c |}
    {c |} Date functions{space 23}{c |} {help date functions}          {c |}
    {c |} Time-series functions{space 16}{c |} {help time-series functions}   {c |}
    {c |} Matrix functions{space 21}{c |} {help matrix functions}        {c |}
    {c BLC}{hline 38}{c BT}{hline 25}{c BRC}


{title:Introduction}

{pstd}
Functions are used in expressions, which are abbreviated {help exp} in
syntax diagrams.  For example, a simplified version of {helpb generate}'s
syntax is

{phang2}{cmd:generate} {it:newvar} {cmd:=} {it:exp}

{pstd}
and thus, one might type "{cmd:generate loginc = ln(income)}".  {cmd:ln()}
is a function.

{pstd}
Functions may be specified in any expression.  The arguments of a function
may be any expression, including other functions.

{pstd}
A function's arguments are enclosed in parentheses and, if there are
multiple arguments, separated by commas.

{pstd}
Functions return {it:missing} ({hi:.}) when the value of the
function is undefined.


{title:Examples}

{phang}{cmd:. generate y = sqrt(abs(z*z-x*x-y))}

{phang}{cmd:. gen str20 new = cond(sex=="m","Mr. ", "Ms. ") + upper(substr(name,1,1)) + lower(substr(name,2,.))}


{title:Also see}

{psee}
Manual:  {bf:[D] functions}

{psee}
Online:  {helpb egen},
{help expressions},
{helpb generate},
{help operators}
{p_end}