dydx.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}
{* 20jan2005}{...}
{cmd:help dydx}, {cmd:help integ} {right:dialogs:  {bf:{dialog dydx}}  {bf:{dialog integ}}}
{hline}

{title:Title}

{p2colset 5 17 19 2}{...}
{p2col :{hi:[R] dydx} {hline 2}}Calculate numeric derivatives and integrals{p_end}
{p2colreset}{...}


{title:Syntax}

{phang}
Derivatives of numeric functions

{p 8 13 2}
{cmd:dydx} {it:yvar} {it:xvar} {ifin} {cmd:,} {opt g:enerate(newvar)} 
[{it:{help dydx##dydx_options:dydx_options}}]

{phang}
Integrals of numeric functions

{p 8 15 2}
{cmd:integ} {it:yvar} {it:xvar} {ifin} [{cmd:,} 
{it:{help dydx##integ_options:integ_options}}]

{synoptset 20 tabbed}{...}
{marker dydx_options}{...}
{synopthdr :dydx_options}
{synoptline}
{syntab :Main}
{p2coldent :* {opth g:enerate(newvar)}}create variable named {it:newvar}{p_end}
{synopt :{opt replace}}overwrite the existing variable{p_end}
{synoptline}
{p2colreset}{...}
{p 4 6 2}* {opt g:enerate(newvar)} is required.

{synoptset 20 tabbed}{...}
{marker integ_options}{...}
{synopthdr :integ_options}
{synoptline}
{syntab :Main}
{synopt :{opth g:enerate(newvar)}}create variable named {it:newvar}{p_end}
{synopt :{opt t:rapezoid}}use trapezodial rule to compute integrals; default is cubic splines{p_end}
{synopt :{opt i:nitial(#)}}initial value of integral; default is {cmd:0}{p_end}
{synopt :{opt replace}}overwrite the existing variable{p_end}
{synoptline}
{p2colreset}{...}

{p 4 6 2}
{opt by} may be used with {cmd:dydx} and {cmd:integ}; see {helpb by}.


{title:Description}

{pstd}
{cmd:dydx} and {cmd:integ} calculate derivatives and integrals of numeric
"functions".


{title:Options}

{dlgtab:Main}

{phang}
{opth generate(newvar)} specifies the name of the new variable to be created.
It must be specified with {cmd:dydx}.

{phang}
{opt trapezoid} requests that the trapezoidal rule (the sum of (x[i] -
x[i-1])(y[i] + y[i-1])/2) be used to compute integrals.  The default is cubic
splines, which give superior results for most smooth functions; for irregular
functions, {opt trapezoid} may give better results.

{phang}
{opt initial(#)} specifies the initial condition for calculating definite
integrals.  If not specified, the initial condition is taken as {cmd:0}.

{phang}
{opt replace} specifies that if an existing variable is specified for 
{opt generate()}, it should be overwritten.


{title:Examples}

{phang}{cmd:. dydx y x, gen(yprime)} {space 9} (create derivative of function){p_end}
{phang}{cmd:. line y yprime x} {space 15} (graph function and derivative)

{phang}{cmd:. integ y x, gen(Sy)} {space 12} (create integral of function){p_end}
{phang}{cmd:. line y Sy x} {space 19} (graph function and integral)


{title:Also see}

{psee}
Manual:  {bf:[R] dydx}

{psee}
Online:  {helpb egen}, {helpb obs}, {helpb range}
{p_end}