[GAP Forum] Is it possible to step through the program, like GNU GDB debugger, against built-in functions(ex. DerivedSubgroup, ClosureSubgroupNC )?

[buynnnmmm1 at yahoo.co.jp]

Dear Stephen Linton,

Thank you very much for your help.

> Performance is one consideration, of course. Another is making use of already 
> computing information about the group when possible. Still another is computing 
> data structures that are likely to be useful for further computations. The GAP 
> library function, having found a group to be solvable will also have constructed 
> a data structure called a Pcgs (PolyCyclic Generating System) which can be used 
> to greatly speed up many further computations with the group.


I am interesting in "PolyCyclic Generating System".
So I'll try to read the source . Although it is doubtful whether I can do understand it.
What you have told me is , seems to me to lower the difficulty of reading the source .
Thank you very much for letting me know clearly the point and Pcgs.


With best regards
buynnnmmm1

----- Original Message -----
> From: Stephen Linton <steve.linton at st-andrews.ac.uk>
> To: buynnnmmm1 at yahoo.co.jp
> Cc: Alexander Konovalov <alexk at mcs.st-andrews.ac.uk>; GAP Forum <forum at gap-system.org>
> Date: 2014/9/17, Wed 22:18
> Subject: Re: [GAP Forum] Is it possible to step through the program, like GNU GDB debugger, against built-in functions(ex. DerivedSubgroup, ClosureSubgroupNC )?
> 
> 
> On 17 Sep 2014, at 13:57, buynnnmmm1 at yahoo.co.jp wrote:
>> 
>>  myIsSolvable:=function ( x )
>>     local  d;
>>     d := DerivedSeries( x );
>>     return IsTrivial( d[Size( d )] );
>>  end
>> 
>> 
>>  gap> List([1..30], x -> myIsSolvable(SymmetricGroup(x))) = 
> List([1..30], x -> IsSolvable(SymmetricGroup(x)));
>>  true
>> 
>>  For Symmetric Group, the same results have been obtained. 
>>  So I'm going to try to do withmyIsSolvable function that uses the 
> DerivedSeries function.
>> 
>>  There was a difference of more than twice the run time to IsSolvable of 
> built-in and myIsSolvable Taking the profile.
>> 
>>  Built-in IsSolved Would has become the source code I hard to understand in 
> order to increase the execution speed?
>> 
> 
> 
> Performance is one consideration, of course. Another is making use of already 
> computing information about the group when possible. Still another is computing 
> data structures that are likely to be useful for further computations. The GAP 
> library function, having found a group to be solvable will also have constructed 
> a data structure called a Pcgs (PolyCyclic Generating System) which can be used 
> to greatly speed up many further computations with the group.
> 
>     Steve
>