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Rounding off decimals to the nearest number in PERL

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# 1  
Old 03-26-2009
Rounding off decimals to the nearest number in PERL
Hi Guys,

I am generating a statistical report , below is the snippet of the code :
Quote:
$sliceStartTime = &convertTime($sTime);
$sliceEndTime = &convertTime($eTime);
$totalTime = $sliceEndTime - $sliceStartTime;
$nSlices = $totalTime / ($slice * 60);

Now, $nSlices stands for the time duration,meaning,the statistics will be displayed for that particular time duration. Trouble is, for certain values of $totalTime (which is the end time - start time ), i end up getting decimal values for $nSlices. I am coding this in PERL, and i wish i could find a way to round off the decimals to the nearest whole number. For example, if the value of $nSlices is 23.323232 i would like to round it off to 23, and if the value of $nSlices is 23.7878787 i would like to round it off to 24. Basically,anything over .5 and above gets rounded off to the next whole number, and anything below .5 gets rounded off to the previous number. Anyways that i can achieve this? Help would be much appreciated!
# 2  
Old 03-26-2009
this might help youSmilie
Code:
echo "$nSlices"|awk '{printf "%d",$0+0.5}'

# 3  
Old 03-26-2009
Quote:
Originally Posted by vidyadhar85
this might help youSmilie
Code:
echo "$nSlices"|awk '{printf "%d",$0+0.5}'

Thank you! Will try it later tonight and let you know, i am not quiet sure about the $0+0.5 part though, does that imply we add a 0.5 constant to every value of $nSlices?
# 4  
Old 03-26-2009
From perlfaq

Quote:
Found in /usr/perl5/5.00503/pod/perlfaq4.pod
Does Perl have a round() function? What about ceil() and floor()? Trig functions?

Remember that int() merely truncates toward 0. For rounding to a
certain number of digits, sprintf() or printf() is usually the
easiest route.

printf("%.3f", 3.1415926535); # prints 3.142

The POSIX module (part of the standard perl distribution)
implements ceil(), floor(), and a number of other mathematical
and trigonometric functions.

use POSIX;
$ceil = ceil(3.5); # 4
$floor = floor(3.5); # 3

In 5.000 to 5.003 Perls, trigonometry was done in the
Math::Complex module. With 5.004, the Math::Trig module (part of
the standard perl distribution) implements the trigonometric
functions. Internally it uses the Math::Complex module and some
functions can break out from the real axis into the complex
plane, for example the inverse sine of 2.

Rounding in financial applications can have serious
implications, and the rounding method used should be specified
precisely. In these cases, it probably pays not to trust
whichever system rounding is being used by Perl, but to instead
implement the rounding function you need yourself.

To see why, notice how you'll still have an issue on half-way-
point alternation:

for ($i = 0; $i < 1.01; $i += 0.05) { printf "%.1f ",$i}

0.0 0.1 0.1 0.2 0.2 0.2 0.3 0.3 0.4 0.4 0.5 0.5 0.6 0.7 0.7
0.8 0.8 0.9 0.9 1.0 1.0

Don't blame Perl. It's the same as in C. IEEE says we have to do
this. Perl numbers whose absolute values are integers under
2**31 (on 32 bit machines) will work pretty much like
mathematical integers. Other numbers are not guaranteed.
# 5  
Old 03-29-2009
Thanks Rikxik! I guess that's gonna work! I am trying to write a logical if else statement in Perl to use the 'ceil' and 'floor' functions , but my novice programming skills is hampering the progress!

This is what i am trying to accomplish , if the value of a variable $nSlice is a number greater than .5 (ex : 23.5 or 16.8 or 17.9 etc), ceil that number,else floor that number. Any suggestions or help would be appreciated. Thanks again!
# 6  
Old 03-29-2009
Quote:
Originally Posted by rdlover
Thanks Rikxik! I guess that's gonna work! I am trying to write a logical if else statement in Perl to use the 'ceil' and 'floor' functions , but my novice programming skills is hampering the progress!

This is what i am trying to accomplish , if the value of a variable $nSlice is a number greater than .5 (ex : 23.5 or 16.8 or 17.9 etc), ceil that number,else floor that number. Any suggestions or help would be appreciated. Thanks again!
More than likely you do not need to use the POSIX module, your numbers do not appear to be that critical or important, using sprintf or printf should work.
# 7  
Old 03-29-2009
Below is the snippet of the code that i have written. The damn sprintf is not working. No matter what number i enter, it is entering ceil and not floor.Any reasons why ?



Code:
#!/usr/bin/perl

# SOME VARIABLE

use POSIX;

print "Enter a number = ";

$nSlices1 = <STDIN>;

($bdec, $adec ) = split( /\./, $nSlices1 ); # Split the variable at the decimal point and put it into 2 temporary variables


print " The value of numbers before decimal point is $bdec \n";

sprintf("%.3f", $adec) ;

print " The value of numbers after  decimal point is $adec \n";


if ($adec >= 50)

{
     $ceil = ceil($nSlices1); 
     print "The value of $nSlices1 has been rounded off to $ceil \n";
    } 

else 

{
      $floor = floor($nSlices1);
        
       print "The value of input has been rounded off to $floor  \n";
        
}
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