mf_diag0cnt.hlp

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{smcl}
{* 18mar2005}{...}
{cmd:help mata diag0cnt()}
{hline}
{* index diag0cnt()}{...}

{title:Title}

{p 4 8 2}
{bf:[M-5] diag0cnt() -- Count zeros on diagonal}


{title:Syntax}

{p 8 12 2}
{it:real scalar}
{cmd:diag0cnt(}{it:real matrix X}{cmd:)}


{title:Description}

{p 4 4 2}
{cmd:diag0cnt(}{it:X}{cmd:)} returns the number of principal diagonal
elements of {it:X} that are 0.


{title:Remarks}

{p 4 4 2}
    {cmd:diag0cnt()} is often used after {bf:{help mf_invsym:[M-5] invsym()}} 
    to count the number of columns dropped due to collinearity.


{title:Conformability}

    {cmd:diag0cnt(}{it:X}{cmd:)}:
	     {it:X}:  {it:r x c}
	{it:result}:  1 {it:x} 1


{title:Diagnostics}

{p 4 4 2}
{cmd:diag0cnt(}{it:X}{cmd:)} returns 0 if {it:X} is void.


{title:Source code}

{p 4 4 2}
{view diag0cnt.mata, adopath asis:diag0cnt.mata}


{title:Also see}

{p 4 13 2}
Manual:  {hi:[M-5] diag0cnt()}

{p 4 13 2}
Online:  help for 
{bf:{help mf_invsym:[M-5] invsym()}};
{bf:{help m4_utility:[M-4] utility}}
{p_end}