Re: Bigger array taking less memory than smaller array
- To: mathgroup at smc.vnet.net
- Subject: [mg27233] Re: Bigger array taking less memory than smaller array
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Tue, 13 Feb 2001 03:35:41 -0500 (EST)
- References: <9686h9$3ps@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Sebastien
> This example disturbs me...
>
> ByteCount[Array[0 &, {20, 10}]]
>
> 4424
>
> ByteCount[Array[0 &, {30, 10}]]
>
>1260
The second array is big enough to be automatically converted to a packed
array internally, the first one is not.
First, repeat your input, giving names to the arrays.
ByteCount[a1=Array[0&,{20,10}]]
4424
ByteCount[a2=Array[0&,{30,10}]]
1260
Check on which is a packed array.
Developer`PackedArrayQ[a1]
False
Developer`PackedArrayQ[a2]
True
Check on the effect of being a packed array.
ByteCount[Developer`ToPackedArray[a1]]
860
ByteCount[Developer`FromPackedArray[a2]]
6624
--
Allan
---------------------
Allan Hayes
Mathematica Training and Consulting
Leicester UK
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565
<Sebastien.deMentendeHorne at electrabel.com> wrote in message
news:9686h9$3ps at smc.vnet.net...
> Hi,
>
> This example disturbs me...
>
> In[233]:=
> ByteCount[Array[0 &, {20, 10}]]
>
> Out[233]=
> 4424
>
> In[234]:=
> ByteCount[Array[0 &, {30, 10}]]
>
> Out[234]=
> 1260
>
> Some considerations about this ?
>
> Sébastien de Menten de Horne | ELECTRABEL
> Tel: ++32 10 48 51 76 | R&D Energy Markets,
> Fax: ++32 10 48 51 09 | Traverse d'Esope, 6
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>