Re^3: The problem of getting the unit vector "Undefined subroutine &main::Normalize"

[NetWallah]

"Normalize" means different things in different contexts.

The one you seek could very well have already been written and available inside a free CPAN module .. You need to set the context, and search.

If you have trouble finding a pre-written one on CPAN, post back here with an explanation of what you expect "Normalize" to do, and what kind of parameters you are passing in .. Monks are eager to help.

It appears you are dealing with Molecular Chemistry - if so perlmol may be of interest.

[windcrazy86]

That's cool, buddy! I am trying to obtain the unit vector of the dipole moment (a vector) using sub Normalize.

 # get dipole moment
     my $dipoleMoment = $setMolecule->DipoleMoment;
       # get the unit vector of dipole moment
     my $direction=Normalize($dipoleMoment);

unit vector＝±a/|a|. For example, if I want to have the unit vector of (2,-3,6), the calculation process is unit vector＝±（2,-3,6)/√4+9+36＝±（2/7，-3/7,6/7）.

$dipoleMoment is a vector with (X, Y, Z), I am trying to have the unit vector of $dipoleMoment, would you please write sub Normalize to fulfill this calculation?

[NetWallah]

Check out Math::Vector::Real.

With the untested code below, you can probably make it "Normalize" for you:

use strict;
use warnings;
use Math::Vector::Real;
 
my $v = V(2,-3,6); # Your example vector

print "Norm  = ", Normalize ($v),"\n";
print "Versor= ", $v->versor(),"\n";

sub Normalize{
  my ($v) = @_; # parameter is a single vector
  
  my $result = $v->div ( $v->abs() );
       # abs of vector (x,y,z)  = sqrt(x**2 + y**2 + z**2)
  return $result;
}

Update 1:Fixed "print" statement (Original post needed +Normalize(), and tested. It works correctly, producing the output:

Norm  = {0.285714285714286, -0.428571428571429, 0.857142857142857}
Versor= {0.285714285714286, -0.428571428571429, 0.857142857142857}

Update 2: I found out that the "versor()" method does exactly the same thing as Normalize() , and both produce identical results.

[roboticus]

windcrazy86:

If you know the formula (i.e., how to create the result by hand) you shouldn't have any difficulty in creating the subroutine yourself. What difficulty are you having with it?

As I see it, you'd start with something like:

sub Normalize {
   my $v = shift;
   my $vSquared = InProduct($v, $v);
   my $divisor = ... square root of  sum of components of vSquared ...
   my $newVec1 = ... vector created by components of v divided by posi
+tive divisor ...
   my $newVec2 = ... vector created by componets of v divided by negat
+ive divisor ...
   .... whatever else is needed ...
   return $stuff;
}

my @dipoleMomentVectors = Normalize($dipoleMoment);

...roboticus

When your only tool is a hammer, all problems look like your thumb.

[windcrazy86]

Thanks, I am new to perl, so I am still reading the tutorial online. I will test your code and see what's going on.

[Anonymous Monk]

The problem is, we don't know your MaterialsScript module, so we'd be guessing. It seems to be a closed-source product of Accelrys, and I don't see any documentation online.

[windcrazy86]

Yeap, you are right. I thought Normalize is a function in accelrys or perl before. However, it seems it's not for both. So I am using perl to write the sub Normalize to get unit vector from vector and it doesn't have relationship to materialsscript module anymore. Because I am new to perl, it takes me time to read related rules in perl and write it

[windcrazy86]

By the way, CPAN and perlmol are very helpful for me, thank you very much!