few questions

[Aron Ahmadia]

Thanks Satish,

That's definitely an easier way to think about it...

~A

On Wed, Feb 27, 2008 at 3:40 PM, Satish Balay <balay at mcs.anl.gov> wrote:
> Just a note on terminology. The difference between shared & dynamic is
>  a bit confusing [esp across windows/linux/mac etc..]. I like to use
>  'shared-libraries' name instead of 'dynamic-libraries', as thats the
>  primary feature of .so/.dylib/.dll etc.
>
>  PETSc configure supports the following options
>
>  --with-shared=0/1 --with-dynamic=0/1
>
>  The dynamic option refers to the using dlopen() to look for function
>  in a sharedlibrary [instead of resolving these functions at link-time]
>
>  If petsc is built with dynamic usage- then PETSC_USE_DYNAMIC_LIBRARIES
>  flag is set in petscconf.h. Shared libs can be identified by looking
>  at the library names.
>
>  Satish
>
>
>
>  On Wed, 27 Feb 2008, Aron Ahmadia wrote:
>
>  > On Wed, Feb 27, 2008 at 2:11 AM, amjad ali <amjad11 at gmail.com> wrote:
>  > > Hello all,
>  > >
>  > > Please answer the following,
>  > >
>  > > 1) What is the difference between static and dynamic versions of petsc?
>  > >
>  >
>  > Start here: http://en.wikipedia.org/wiki/Library_(computer_science)#Static_libraries
>  >
>  > In PETSc the primary differences end up being the size and link-time.
>  > Statically-linked executables need all the possible code that they
>  > could contain in the actual file, so they can be up to several MB in
>  > size.  Dynamically-linked executables are much leaner for the small
>  > price of a little extra load time.
>  >
>  > Now if you're talking about Dynamically-Loaded code, that's a bit hairier...
>  >
>  > > 2) How to check that which version (static or dynamic) is installed on a
>  > > system?
>  > >
>  >
>  > The fastest way is probably to look in $PETSC_DIR/$PETSC_ARCH/
>  >
>  > If you see .a files, you've got static libraries, if you see .so or
>  > .dylib files you've got dynamic libraries.
>  >
>  > > 3) Plz comment on if there is any effect of static/dynamic version while
>  > > using/calling petsc from some external package?
>  > >
>  >
>  > I'm not sure what you're asking here.  If you mean "Is there a
>  > difference between calling dynamically compiled PETSc from statically
>  > compiled PETSc" the answer is no.  There are differences in how you
>  > compile and link the two version but your actual code would look the
>  > same.
>  >
>  > Again, if we're talking about dynamically loaded code (using something
>  > like dl_open), then your code will look different.
>  >
>  > > 4) how to update an already installed petsc version with newerer/latest
>  > > version of petsc?
>  > >
>  >
>  > Doing this in place is more trouble than it's worth if you're not
>  > using a development copy .  I just grab the latest copy of PETSc from
>  > their webpage, then re-build and re-install.
>  >
>  > ~A
>  >
>  >
>
>