[Ubuntu-BR] mais uma vez sobre 32 ou 64 bits

[Leandro Marino]

*Tenho utilizado constantemente o R em 64 e 32 bits sem problemas.
Eventualmente alguns pacotes não estão disponíveis para 64 bits.

Quanto aos problemas mencionados, como falado anteriormente, não existem
mais.

Tenho um projetozinho (muito básico) que para facilitar já tem o R, Gretl,
MySql, LaTeX entre outros já instalados por padrão, por enquanto apenas
disponível em 32 bits.

http://sourceforge.net/projects/ubuntuforstats/

Agora qual a configuração do seu computador? Nem todo processador suporta
64bits! Cabe salientar também que, no caso do R, algumas contas são mais
lentas em 64 bits.

Direto do FAQ do R:

* 2.28 Should I run 32-bit or 64-bit R?

For most users (especially beginners) we would recommend using the 32-bit
build.

The advantage of a native 64-bit application is that it gets a 64-bit
address space and hence can address far more than 4GB (how much depends on
the version of Windows, but in principle 8TB). This allows a single process
to take advantage of more than 4GB of RAM (if available) and for R's memory
manager to more easily handle large objects (in particular those of 1GB or
more). The disadvantages are that all the pointers are 8 rather than 4 bytes
and so small objects are larger and more data has to be moved around, and
that less external software is available for 64-bit versions of the OS.

The toolchain (compilers, linkers, ...) used to build 64-bit R is less
mature than that for 32-bit R, but testing so far (and all the CRAN packages
provide an extensive test suite) suggests that they are mature enough for
production use. The compilers are able to take advantage of extra features
of all x86-64 chips (more registers, SSE2/3 instructions, ...) and so the
code may run faster despite using larger pointers.

For advanced users the choice may be dictated by whether the contributed
packages needed are available in 64-bit builds (and if they are not that is
some indication that installing them from sources is problematic). At the
time of writing the most commonly-used CRAN packages without 64-bit versions
were BRugs and rggobi. The considerations can be more complex: for example
32/64-bit RODBC need 32/64 ODBC drivers respectively, and where both exist
they may not be able to be installed together. An extreme example is the
Microsoft Access/Excel ODBC drivers: if you have installed 64-bit Microsoft
Office you can only install the 64-bit drivers and so need to use 64-bit
RODBC and hence R.

 2.29 Can both 32- and 64-bit R be installed on the same machine?

Obviously, only relevant if the machine is running a 64-bit version of
Windows – simply select both when using the installer. You can also go back
and add 64-bit components to a 32-bit install.

For many Registry items, 32- and 64-bit programs have different views of the
Registry, but clashes can occur. The most obvious problem is the file
association, which will use the last installation for which this option is
selected, and if that was for an installation of both, will use 32-bit R.

*

*Atenciosamente,
Leandro Marino
http://www.leandromarino.com.br (Fotógrafo)
http://est.leandromarino.com.br/Blog (Estatístico)
Cel.: + 55 21 9845-7707
Cel.: + 55 21 8777-7907