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 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 \*(C`[11,22,33]\*(C', $d will be \*(C`[9,18,27]\*(C'.

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 \s-1HISTORY\s0 $Log: VecStat.pm,v $ Revision 1.9 2003/04/20 00:49:00 [email protected] Perl 5.8 broke test 36, exposing inconsistency in C<median>. Fixed, thanks to [email protected].

Revision 1.8 2001/01/26 11:10:00 [email protected] Added function median. Fixed test, thanks to Andreas Marcel Riechert <[email protected]>

Revision 1.7 2000/10/24 15:28:00 [email protected] Added functions allequal diffbyelement Created a reasonable test suite.

Revision 1.6 2000/06/29 16:06:37 [email protected] 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 <[email protected]> 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 <[email protected]> Andrea Spinelli <[email protected]>