m2_while.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}
{* 18mar2005}{...}
{cmd:help m2 while}
{hline}
{* index while tt}{...}

{title:Title}

{p 4 4 2}
{bf:[M-2] while -- while (exp) stmt}


{title:Syntax}

	{cmd:while (}{it:exp}{cmd:)} {it:stmt}


	{cmd:while (}{it:exp}{cmd:) {c -(}}
		{it:stmts}
	{cmd:{c )-}}


{p 4 4 2}
where {it:exp} must evaluate to a real scalar.


{title:Description}

{p 4 4 2}
{cmd:while} executes {it:stmt} or {it:stmts} zero or more times.  The loop
continues as long as {it:exp} is not equal to zero.


{title:Remarks}

{p 4 4 2}
To understand {cmd:while}, enter the following program

	{cmd}function example(n)
	{
		i = 1
		while (i<=n) {
			printf("i=%g\n", i)
			i++
		}
		printf("done\n")
	}{txt}

{p 4 4 2}
and run {cmd:example(3)}, {cmd:example(2)}, {cmd:example(1)}, 
{cmd:example(0)}, and {cmd:example(-1)}.

{p 4 4 2}
One common use of {cmd:while} is to loop until convergence:

	{cmd}while (mreldif(a, lasta)>1e-10) {
			lasta = a 
			a = {txt}...
	{cmd:{c )-}}


{title:Also see}

{p 4 13 2}
Manual:  {hi:[M-2] while}

{p 4 13 2}
Online:  help for 
{bf:{help m2_semicolons:[M-2] semicolons}},
{bf:{help m2_do:[M-2] do}},
{bf:{help m2_for:[M-2] for}},
{bf:{help m2_break:[M-2] break}},
{bf:{help m2_continue:[M-2] continue}};
{bf:{help m2_intro:[M-2] intro}}
{p_end}