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64-bit vs. 32-bit Matlab

I am wondering if 64-bit Matlab in 64-bit OS compiles faster things? Than 32-bit Matlab in 32-bit OS if the machine is the same one!!! If no... what are the advantages that  64-bit Matlab with 64-bit OS brings us???
0
Sofia
12/6/2010 7:53:06 PM
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"Sofia Häggberg" <hd.int.assNOSPAM@gmail.com> wrote in message <idjev2$sp6$1@fred.mathworks.com>...
> I am wondering if 64-bit Matlab in 64-bit OS compiles faster things? Than 32-bit Matlab in 32-bit OS if the machine is the same one!!! 

Generally 64-bit is slower.

>If no... what are the advantages that  64-bit Matlab with 64-bit OS brings us???

Capability to address larger memory than the limit of 2-4 Gbytes, thus solving very big problem.

Bruno
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Bruno
12/6/2010 8:05:09 PM
On 10-12-06 02:05 PM, Bruno Luong wrote:
> "Sofia H=C3=A4ggberg" <hd.int.assNOSPAM@gmail.com> wrote in message
> <idjev2$sp6$1@fred.mathworks.com>...
>> I am wondering if 64-bit Matlab in 64-bit OS compiles faster things?
>> Than 32-bit Matlab in 32-bit OS if the machine is the same one!!!
>
> Generally 64-bit is slower.
>
>> If no... what are the advantages that 64-bit Matlab with 64-bit OS
>> brings us???
>
> Capability to address larger memory than the limit of 2-4 Gbytes, thus
> solving very big problem.

It will depend upon the hardware details -- though it would not surprise =
me if=20
these days the only supported hardware that differs is the 32 bit MacOS P=
PC=20
version.

When 64 bit code is used, 64 bit pointers have to be loaded and stored. I=
t is=20
not uncommon on processors for that to take longer than saving and loadin=
g 32=20
bit pointers, because more data has to be transferred across the bus.=20
Depending on the instruction set, 64 bit code might also lead to longer=20
instructions in some cases, instructions that can deal with offsets large=
r=20
than 32 bits.

Thus, it is not unreasonable for 64 bit code to end up being larger and s=
lower=20
than 32 bit code. But as Bruno indicates, if you have the memory then 64 =
bit=20
code can be used to solve larger problems. It doesn't take much before yo=
u run=20
in to the 32 bit limits -- on Windows, with the way that Matlab 32 bit us=
es=20
memory, it is common to start out with a maximum array size less than 800=
=20
megabytes.

High performance processors tend to be tuned for 64 bit (or larger) loads=
 and=20
stores, and on them 32 bit loads and stores can end up taking more time. =
You=20
have to know the details of your particular processor model (not just fam=
ily)=20
in order to figure out which would be best for a particular purpose.

0
Walter
12/6/2010 8:23:43 PM
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