This is an excerpt from the latest version perlfaq4.pod, which
comes with the standard Perl distribution. These postings aim to
reduce the number of repeated questions as well as allow the community
to review and update the answers. The latest version of the complete
perlfaq is at http://faq.perl.org .

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4.6: Why doesn't & work the way I want it to?

The behavior of binary arithmetic operators depends on whether they're
used on numbers or strings. The operators treat a string as a series of
bits and work with that (the string "3" is the bit pattern 00110011).
The operators work with the binary form of a number (the number 3 is
treated as the bit pattern 00000011).

So, saying "11 & 3" performs the "and" operation on numbers (yielding
3). Saying "11" & "3" performs the "and" operation on strings (yielding
"1").

Most problems with "&" and "|" arise because the programmer thinks they
have a number but really it's a string. The rest arise because the
programmer says:

I try to calculate the standard deviation of average of C2:C35.
But I get random range in the worksheet G$i. It's not showing as:

D2 =STDEVA(C2:C35,D2)
D3 =STDEVA(C2:C35,D3)
.....

It's showing as:

D2 =STDEVA(C2:C35,D2)
D3 =STDEVA(C2:C31,D3)
D4 =STDEVA(C2:C33,D4)
.....

Any one know why? I tried with " " doesn't help and q { } show nothing
since it's like ' '.

Thanks.

This is an excerpt from the latest version perlfaq4.pod, which
comes with the standard Perl distribution. These postings aim to
reduce the number of repeated questions as well as allow the community
to review and update the answers. The latest version of the complete
perlfaq is at http://faq.perl.org .

--------------------------------------------------------------------

4.10: Why aren't my random numbers random?

If you're using a version of Perl before 5.004, you must call "srand"
once at the start of your program to seed the random number generator.

BEGIN { srand() if $] < 5.004 }

5.004 and later automatically call "srand" at the beginning. Don't call
"srand" more than once--you make your numbers less random, rather than
more.

Hello,

There's a problem while I'm processing sequences. My file content.

ATGCCCTGACGTAAACGTAGGCTACG

GCATGCCCTACGGGTACCCCAGTA

And I hope I can reverse the sequences to be this.

GCATCGGATGCAAATGCAGTCCCGTA

ATGACCCCATGGGCATCCCGTACG

I use "reverse" to do this, but it dose not work any more.
So could you tell me how to solve this problem?

Thank you very much~

Regards,

Amy Lee

This is an excerpt from the latest version perlfaq3.pod, which
comes with the standard Perl distribution. These postings aim to
reduce the number of repeated questions as well as allow the community
to review and update the answers. The latest version of the complete
perlfaq is at http://faq.perl.org .

--------------------------------------------------------------------

3.19: How can I make my CGI script more efficient?

Beyond the normal measures described to make general Perl programs
faster or smaller, a CGI program has additional issues. It may be run
several times per second. Given that each time it runs it will need to
be re-compiled and will often allocate a megabyte or more of system
memory, this can be a killer. Compiling into C isn't going to help you
because the process start-up overhead is where the bottleneck is.

There are two popular ways to avoid this overhead. One solution involves
running the Apache HTTP server (available from http://www.apache.org/ )
with either of the mod_perl or mod_fastcgi plugin modules.

I am using (roughly) the following code.

my %%counter = () ;

$counter{label11}{parent} = 'label1' ;
$counter{label11}{hits} = 14 ;
$counter{label12}{parent} = 'label1' ;
$counter{label12}{hits} = 14 ;

If I use: for my $key(keys %%counter), I get label11 and label12 as
values.
I would like to run something like: foreach my $key(keys %%
($counter(label11) ) )
and get 'parent' and 'hits' as the sub-keys.

Is there any quick way to do this but quicker than what? So let's say
is there a 'standard way' in which this is done? Or do I have to do it
the 'hard way' ? Define a sub-hash, and then assign it to the parent
hash as its key's value?

This is an excerpt from the latest version perlfaq4.pod, which
comes with the standard Perl distribution. These postings aim to
reduce the number of repeated questions as well as allow the community
to review and update the answers. The latest version of the complete
perlfaq is at http://faq.perl.org .

--------------------------------------------------------------------

4.7: How do I multiply matrices?

Use the Math::Matrix or Math::MatrixReal modules (available from CPAN)
or the PDL extension (also available from CPAN).

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are not necessarily experts in every domain where Perl might show up,
so please include as much information as possible and relevant in any
corrections. The perlfaq-workers also don't have access to every
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corrections to examples that do not work on particular platforms.
Working code is greatly appreciated.

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