mf_j.hlp

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{smcl}
{* 28mar2005}{...}
{cmd:help mata J()}
{hline}
{* index J()}{...}

{title:Title}

{p 4 4 2}
{bf:[M-5] J() -- Matrix of constants}


{title:Syntax}

{p 8 12 2}
{it:transmorphic matrix}
{cmd:J(}{it:real scalar r}{cmd:,}
{it:real scalar c}{cmd:,}
{it:scalar val}{cmd:)}


{title:Description}

{p 4 4 2}
{cmd:J(}{it:r}{cmd:,} {it:c}{cmd:,} {it:val}{cmd:)}
returns an {it:r x c} matrix with each element equal to {it:val}.


{title:Remarks}

{p 4 4 2}
Note that {cmd:J()} must be typed in uppercase.

{p 4 4 2}
{cmd:J()} can create any type of matrix:

        function         returns
	{hline 66}
	{cmd:J(2, 3, 4)}       2 x 3 real    matrix, each element = 4
        {cmd:J(2, 3, 4+5i)}    2 x 3 complex matrix, each element = 4+5i
        {cmd:J(2, 3, "hi")}    2 x 3 string  matrix, each element = "hi"
	{cmd:J(2, 3, &x)}      2 x 3 pointer matrix, each element = address of {cmd:x}
	{hline 66}

{p 4 4 2}
In addition, {cmd:J()} can create void matrices:

	{cmd:J(0, 0, .)}       0 {it:x} 0 real 
	{cmd:J(0, 1, .)}       0 {it:x} 1 real 
	{cmd:J(1, 0, .)}       1 {it:x} 0 real 

	{cmd:J(0, 0, 1i)}      0 {it:x} 0 complex 
	{cmd:J(0, 1, 1i)}      0 {it:x} 1 complex 
	{cmd:J(1, 0, 1i)}      1 {it:x} 0 complex 

	{cmd:J(0, 0, "")}      0 {it:x} 0 string 
	{cmd:J(0, 1, "")}      0 {it:x} 1 string 
	{cmd:J(1, 0, "")}      1 {it:x} 0 string 

	{cmd:J(0, 0, NULL)}    0 {it:x} 0 pointer 
	{cmd:J(0, 1, NULL)}    0 {it:x} 1 pointer 
	{cmd:J(1, 0, NULL)}    1 {it:x} 0 pointer 

{p 4 4 2}
See {bf:{help m2_void:[M-2] void}}.


{title:Conformability}

    {cmd:J(}{it:r}{cmd:,} {it:c}{cmd:,} {it:val}{cmd:)}:
		{it:r}:  1 {it:x} 1
		{it:c}:  1 {it:x} 1
	      {it:val}:  1 {it:x} 1
	   {it:result}:  {it:r x c}


{title:Diagnostics}

{p 4 4 2}
{cmd:J(}{it:r}{cmd:,} {it:c}{cmd:,} {it:val}{cmd:)} 
aborts with error if {it:r}<0 or {it:c}<0, or 
if {it:r}>={cmd:.} or {it:c}>={cmd:.}.
Arguments {it:r} and {it:c} are interpreted as 
{cmd:trunc(}{it:r}{cmd:)} and 
{cmd:trunc(}{it:c}{cmd:)}.


{title:Also see}

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

{p 4 13 2}
Online:  help for 
{bf:{help mf_missingof:[M-5] missingof()}};
{bf:{help m4_matrix:[M-4] matrix}}
{p_end}