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how to generate random number in Fortran ?

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Old   April 1, 2003, 10:14
Default how to generate random number in Fortran ?
  #1
tang
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Any one has experience to generate a random number in Fortran? using

random_number(a), ...

What's the details?

Thanks

tang
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Old   April 1, 2003, 13:47
Default Re: how to generate random number in Fortran ?
  #2
R. Andom.
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Check Numerical Recipes in FORTRAN online......
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Old   April 2, 2003, 09:48
Default Re: how to generate random number in Fortran ?
  #3
littlelz
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for fortran 90, use: CALL RANDOM_NUMBER(random), then the variable random can be used!
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Old   April 2, 2003, 09:54
Default Re: how to generate random number in Fortran ?
  #4
tang
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but use

CALL RANDOM_NUMBER

gives a same number at different runs. That is, it is not random if different runs are made.

Using 'seed' may solve the problem? then how?

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Old   April 2, 2003, 11:12
Default Re: how to generate random number in Fortran ?
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Vladimir Krejci
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I am not sure but all random number generators produce the same number if you use the same number for their initialization. If you want to get a number which is more random (for you) initialize the generator with e.g. actual time on your computer.

hope it helps

vladimir
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Old   April 2, 2003, 11:23
Default Re: how to generate random number in Fortran ?
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tang
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But how to set actual time as the seed? What's the command in Fortran?

Thanks

T
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Old   April 2, 2003, 17:48
Default Re: how to generate random number in Fortran ?
  #7
Nashat
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These links might be helpful:

http://rsc.anu.edu.au/~harry/COURSES...TH/node73.html

http://www.fortran.com/fortran/random1.f90

http://www.fortran.com/fortran/random2.f90

http://www.fortran.com/fortran/kiss.f90

http://www.library.cornell.edu/nr/nr_index.cgi

The system random generator is sometimes not as random as you would like it to be. The routines in Numerical Recepies are pretty good.

Regards.
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Old   April 2, 2003, 17:58
Default thanks to your all three
  #8
tang
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Dear Nashat, etc

Thanks a lot

T
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