VecStat(3pm)						User Contributed Perl Documentation					      VecStat(3pm)

NAME

	   Math::VecStat - Some basic numeric stats on vectors

SYNOPSIS

	   use Math::VecStat qw(max min maxabs minabs sum average);
	   $max=max(@vector);
	   $max=max(@vector);
	   ($max,$imax)=max(@vector);
	   ($max,$imax)=max(@vector);
	   $min=min(@vector);
	   $min=min(@vector);
	   ($max,$imin)=min(@vector);
	   ($max,$imin)=min(@vector);
	   $max=maxabs(@vector);
	   $max=maxabs(@vector);
	   ($max,$imax)=maxabs(@vector);
	   ($max,$imax)=maxabs(@vector);
	   $min=minabs(@vector);
	   $min=minabs(@vector);
	   ($max,$imin)=minabs(@vector);
	   ($max,$imin)=minabs(@vector);
	   $sum=sum($v1,$v2,...);
	   $sum=sum(@vector);
	   $sum=sum(@vector);
	   $average=average($v1,$v2,...);
	   $av=average(@vector);
	   $av=average(@vector);
	   $ref=vecprod($scalar,@vector);
	   $ok=ordered(@vector);
	   $ok=ordered(@vector);
	   $ref=sumbyelement(@vector1,@vector2);
	   $ref=diffbyelement(@vector1,@vector2);
	   $ok=allequal(@vector1,@vector2);
	   $ref=convolute(@vector1,@vector2);

DESCRIPTION

       This package provides some basic statistics on numerical vectors. All the subroutines can take a reference to the vector to be operated on.
       In some cases a copy of the vector is acceptable, but is not recommended for efficiency.

       max(@vector), max(@vector)
	    return the maximum value of given values or vector. In an array context returns the value and the index in the array where it occurs.

       min(@vector), min(@vector)
	    return the minimum value of given values or vector, In an array context returns the value and the index in the array where it occurs.

       maxabs(@vector), maxabs(@vector)
	    return the maximum value of absolute of the given values or vector. In an array context returns the value and the index in the array
	    where it occurs.

       minabs(@vector), minabs(@vector)
	    return the minimum value of the absolute of the given values or vector. In an array context returns the value and the index in the
	    array where it occurs.

       sum($v1,$v2,...), sum(@vector), sum(@vector)
	    return the sum of the given values or vector

       average($v1,$v2,..), average(@vector), average(@vector)
	    return the average of the given values or vector

       vecprod($a,$v1,$v2,..), vecprod($a,@vector), vecprod( $a, @vector )
	    return a vector built by multiplying the scalar $a by each element of the @vector.

       ordered($v1,$v2,..), ordered(@vector), ordered(@vector)
	    return nonzero iff the vector is nondecreasing with respect to its index.  To be used like

	      if( ordered( $lowBound, $value, $highBound ) ){

	    instead of the (slightly) more clumsy

	      if( ($lowBound <= $value) && ($value <= $highBound) ) {

       sumbyelement( @array1, @array2 ), diffbyelement(@array1,@array2)
	    return the element-by-element sum or difference of two identically-sized vectors. Given

	      $s = sumbyelement( [10,20,30], [1,2,3] );
	      $d = diffbyelement( [10,20,30], [1,2,3] );

	    $s will be "[11,22,33]", $d will be "[9,18,27]".

       allequal( @array1, @array2 )
	    returns true if and only if the two arrays are numerically identical.

       convolute( @array1, @array2 )
	    return a reference to an array containing the element-by-element product of the two input arrays. I.e.,

	      $r = convolute( [1,2,3], [-1,2,1] );

	    returns a reference to

	      [-1,4,3]

       median
	    evaluates the median, i.e. an element which separates the population in two halves.  It returns a reference to a list whose first
	    element is the median value and the second element is the index of the median element in the original vector.

	      $a = Math::VecStat::median( [9,8,7,6,5,4,3,2,1] );

	    returns the list reference

	      [ 5, 4 ]

	    i.e. the median value is 5 and it is found at position 4 of the original array.

	    If there are several elements of the array having the median value, e.g. [1,3,3,3,5].  In this case we choose always the first element
	    in the original vector which is a median. In the example, we return [3,1].	=back =head1 HISTORY

	     $Log: VecStat.pm,v $
	     Revision 1.9  2003/04/20 00:49:00 spinellia@acm.org
	     Perl 5.8 broke test 36, exposing inconsistency in C<median>.  Fixed, thanks to david@jamesgang.com.

	     Revision 1.8  2001/01/26 11:10:00 spinellia@acm.org
	     Added function median.
	     Fixed test, thanks to Andreas Marcel Riechert <riechert@pobox.com>

	     Revision 1.7  2000/10/24 15:28:00	spinellia@acm.org
	     Added functions allequal diffbyelement
	     Created a reasonable test suite.

	     Revision 1.6  2000/06/29 16:06:37	spinellia@acm.org
	     Added functions vecprod, convolute, sumbyelement

	     Revision 1.5  1997/02/26 17:20:37	willijar
	     Added line before pod header so pod2man installs man page correctly

	     Revision 1.4  1996/02/20 07:53:10	willijar
	     Added ability to return index in array contex to max and min
	     functions. Added minabs and maxabs functions.
	     Thanks to Mark Borges <mdb@cdc.noaa.gov> for these suggestions.

	     Revision 1.3  1996/01/06 11:03:30	willijar
	     Fixed stupid bug that crept into looping in min and max functions

	     Revision 1.2  1995/12/26 09:56:38	willijar
	     Oops - removed xy data functions.

	     Revision 1.1  1995/12/26 09:39:07	willijar
	     Initial revision

BUGS

       Let me know. I welcome any appropriate additions for this package.

AUTHORS

       John A.R. Williams <J.A.R.Williams@aston.ac.uk> Andrea Spinelli <spinellia@acm.org>

perl v5.12.4							    2011-07-11							      VecStat(3pm)