Re: RandomReplacement
- To: mathgroup at smc.vnet.net
- Subject: [mg51665] Re: RandomReplacement
- From: sean kim <sean_incali at yahoo.com>
- Date: Wed, 27 Oct 2004 23:44:42 -0400 (EDT)
- Reply-to: sean_incali at yahoo.com
- Sender: owner-wri-mathgroup at wolfram.com
hi andrej and everyone
I'm starting to think *maybe* the PackedArray isn't
the problem. To reproduce the problem...
In[1]:= SeedRandom[5];
Timing[First[real1=Table[Random[],{249}]]]
Developer`PackedArrayQ[real1]
Out[2]= {0. Second,0.786599}
Out[3]= False
In[4]:= SeedRandom[5];
Timing[First[real2=Table[Random[],{250}]]]
Developer`PackedArrayQ[real2]
Out[5]= {0. Second,0.786599}
Out[6]= True
and there it is.
now...
Quit
In[1]:= Needs["Statistics`ContinuousDistributions`"];
In[2]:= uni= UniformDistribution[0, 1]
Out[2]= UniformDistribution[0,1]
In[3]:= SeedRandom[5];
Timing[First[uni1=Table[Random[uni],{249}]]]
Developer`PackedArrayQ[uni1]
Out[4]= {0. Second,0.786599}
Out[5]= False
In[6]:= SeedRandom[5];
Timing[First[uni2=Table[Random[uni],{250}]]]
Developer`PackedArrayQ[uni2]
Out[7]= {0.01 Second,0.786599}
Out[8]= False
Without loading RandomReplacement, we see the
packedarray problem is no longer present if we change
way we use the Random.
Needs["Statistics`ContinuousDistributions`"];
uni= UniformDistribution[0, 1]
Random[uni]
should be identical to Random[] ( according to help)
but once we load the RandomReplacement,
Quit
In[1]:= <<RandomReplacement.m
In[2]:= SeedRandom[5];
Timing[First[real3=Table[Random[],{249}]]]
Developer`PackedArrayQ[real3]
Timing[First[real4=Table[Random[],{250}]]]
Developer`PackedArrayQ[real4]
Out[3]= {0. Second,0.66205}
Out[4]= False
Out[5]= {0. Second,0.793703}
Out[6]= True
problem with packedarray is still there.
but the package *does* solve the problems reported in
posts,
http://groups.google.com/groups?hl=en&lr=&newwindow=1&safe=off&threadm=b8vrqe%24dit%241%40smc.vnet.net&rnum=3&prev=/groups%3Fhl%3Den%26lr%3D%26newwindow%3D1%26safe%3Doff%26q%3Drandom%2Bcorrelation%26meta%3Dgroup%253Dcomp.soft-sys.math.mathematica
and
http://groups.google.com/groups?hl=en&lr=&newwindow=1&safe=off&threadm=a61v9o%24gq4%241%40smc.vnet.net&rnum=1&prev=/groups%3Fhl%3Den%26lr%3D%26newwindow%3D1%26safe%3Doff%26q%3Drandom%2Bfishy%26meta%3Dgroup%253Dcomp.soft-sys.math.mathematica
while the PackedAray problem persists.
Using,
Needs["Statistics`ContinuousDistributions`"];
uni= UniformDistribution[0, 1]
Random[uni]
in the above cases, doesn't get fix the probloem btw.
and if it's "getting around the packedArray" that's
slowing things down, perhaps there is no need for that
step? ( since the current package doesn't get around
it)
I don't know.
wanted to hear everyone's thoughts on it.
sean
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