mf_isdiagonal.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 mata isdiagonal()}
{hline}
{* index diagonal matrix}{...}
{* index isdiagonal()}{...}

{title:Title}

{p 4 8 2}
{bf:[M-5] isdiagonal() -- Whether matrix is diagonal}


{title:Syntax}

{p 8 12 2}
{it:real scalar}
{cmd:isdiagonal(}{it:numeric matrix A}{cmd:)}


{title:Description}

{p 4 4 2}
{cmd:isdiagonal(}{it:A}{cmd:)} returns 1 if {it:A} has only zeros
off the principal diagonal and returns 0 otherwise.
{cmd:isdiagonal()} may be used with
either real or complex matrices.


{title:Remarks}

{p 4 4 2}
See {bf:{help mf_diag:[M-5] diag()}}
for making diagonal matrices out of vectors or out of nondiagonal matrices; 
see {bf:{help mf_diagonal:[M-5] diagonal()}}
for extracting the diagonal of a matrix into a vector.

{title:Conformability}

    {cmd:isdiagonal(}{it:A}{cmd:)}:
		{it:A}:  {it:r x c}
	   {it:result}:  1 {it:x} 1


{title:Diagnostics}

{p 4 4 2}
{cmd:isdiagonal(}{it:A}{cmd:)} returns 1 if {it:A} is void.


{title:Source code}

{p 4 4 2}
{view isdiagonal.mata, adopath asis:isdiagonal.mata}.


{title:Also see}

{p 4 13 2}
Manual:  {hi:[M-5] isdiagonal()}

{p 4 13 2}
Online:  help for 
{bf:{help mf_diag:[M-5] diag()}},
{bf:{help mf_diagonal:[M-5] diagonal()}};
{bf:{help m4_utility:[M-4] utility}}
{p_end}