Re: [ALPS-users] SEED Parameter

21 Jan 2012

      Dear Matthias,

Thank you for your answer. But I think I did not made myself clear.

I used the same input file , and ran it twice with alps 1.35 obtaining
different results in each run. Using the same input file and running twice
with alps 2.00.rc4 I got different results. All 4 results were different
from each other.

I could not obtain exactly the same results even using the same code and
the same SEED in either versions. Am I doing something wrong? Or the result
could never actually be the same?

In case it helps, this is the input file used in all runs:
FILE:parameter

LATTICE="simple cubic lattice"
MODEL   = "spin"
ALGORITHM="sse"
MEASURE[Structure Factor]=false
MEASURE[Correlations]=false
MEASURE[Specific Heat]=true
MEASURE[Stiffness]=true
MEASURE[Magnetization]=true
WHICH_LOOP_TYPE="locopt"
EPSILON=0.5
local_S=1
J=-1
J0=-1
J1=-1
Jz=0
Jz'=0
{THERMALIZATION=10000;L=04;BETA=0.10;SWEEPS=1000;D=10.0;SEED=814}

I converted it with parameter2xml

Then I executed the dirloop_see v1.1 for alps 1.3.5:
dirloop_sse --Tmin=10 parameter.in.xml

with the result:
...
   <SCALAR_AVERAGE name="Energy">
      <COUNT>8519</COUNT>
      <MEAN method="simple">250.472</MEAN>
...
Then I repeated the command:
dirloop_sse --Tmin=10 parameter.in.xml

and obtained the result:
...
<SCALAR_AVERAGE name="Energy">
      <COUNT>3009</COUNT>
      <MEAN method="simple">250.553</MEAN>
...

The same goes for the dirloop 4.1 based on alps 2.0.0rc4 code:
same parameters same SEED:

 After extracting values with "convert2xml parameter.task1.out.run1"  the
1st run produced:
<SCALAR_AVERAGE name="Energy">
      <COUNT>1473</COUNT>
      <MEAN method="simple">251.784</MEAN>

And in the 2nd run:
 <SCALAR_AVERAGE name="Energy">
      <COUNT>16076</COUNT>
      <MEAN method="simple">250.616</MEAN>

Marcelo Guimarães

2012/1/21 Matthias Troyer <troyer@phys.ethz.ch>
...
Hi Marcello,
Indeed if the same SEED is used you get the same results if the same code
is taken. However, dirloop_sse was completely rewritten between 1.3 and
2.0. It is a new code. Thus the results should now only agree within error
bars.
Matthias
On Jan 20, 2012, at 6:56 PM, Marcelo Guimarães wrote:
...
Dear All,
I was wondering if using the same SEED parameter with the dirloop_sse
application in different runs should produce exactly the same results.
It is defined as " The random number seed used in the next run.". But I
failed to produce the same results with alps 1.35 or with alps 2.02.
Regards,
Marcelo Guimarães