07-13-2010
Doubt in Perl Variable declaration
Anyone please say what is the difference between $var and ${var} in perl
Sometimes $var used and sometimes ${var} used in same program.
Thanks in Advance,
Prabhu
---------- Post updated at 09:34 AM ---------- Previous update was at 05:59 AM ----------
Any one please clarify
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LEARN ABOUT DEBIAN
statistics::basic::variance
Statistics::Basic::Variance(3pm) User Contributed Perl Documentation Statistics::Basic::Variance(3pm)
NAME
Statistics::Basic::Variance - find the variance of a list
SYNOPSIS
Invoke it this way:
my $variance = variance(1,2,3);
Or this way:
my $v1 = vector(1,2,3);
my $var = var($v1);
And then either query the values or print them like so:
print "The variance of $v1: $variance
";
my $vq = $var->query;
my $v0 = 0+$var;
Create a 20 point "moving" variance like so:
use Statistics::Basic qw(:all nofill);
my $sth = $dbh->prepare("select col1 from data where something");
my $len = 20;
my $var = var()->set_size($len);
$sth->execute or die $dbh->errstr;
$sth->bind_columns( my $val ) or die $dbh->errstr;
while( $sth->fetch ) {
$var->insert( $val );
if( defined( my $v = $var->query ) ) {
print "Variance: $v
";
}
# This would also work:
# print "Variance: $v
" if $var->query_filled;
}
METHODS
new()
The constructor takes a list of values, a single array ref, or a single Statistics::Basic::Vector as arguments. It returns a
Statistics::Basic::Variance object.
Note: normally you'd use the mean() constructor, rather than building these by hand using "new()".
query_mean()
Returns the Statistics::Basic::Mean object used in the variance computation.
_OVB::import()
This module also inherits all the overloads and methods from Statistics::Basic::_OneVectorBase.
AUTHOR
Paul Miller "<jettero@cpan.org>"
I am using this software in my own projects... If you find bugs, please please please let me know. :) Actually, let me know if you find it
handy at all. Half the fun of releasing this stuff is knowing that people use it.
OVERLOADS
This object is overloaded. It tries to return an appropriate string for the calculation or the value of the computation in numeric
context.
In boolean context, this object is always true (even when empty).
COPYRIGHT
Copyright 2012 Paul Miller -- Licensed under the LGPL
SEE ALSO
perl(1), Statistics::Basic, Statistics::Basic::_OneVectorBase, Statistics::Basic::Vector
perl v5.14.2 2012-01-23 Statistics::Basic::Variance(3pm)