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Hello, I have asked this on the forum for Windows as well (see https://software.intel.com/en-us/node/add/forum/36933 for the discussion there), but I ran into the following problem with the random number generator and coarrays (text copied forr the Windows forum):
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I have run into a small riddle. I was trying to use the random_number subroutine in a small program using coarrays and discovered that on Linux, with the Intel compiler version I have access to, 18.0.3, the random numbers on each image are the same (well, sometimes I see two sets but not clearly independent sequences). When I try this on Windows (version 18.0.5) , I do get independent random numbers. In both cases I use random_seed to initialise the random number generator. Here is a small demo program:
program chkrandom implicit none real :: r call random_seed call random_number( r ) write(*,*) this_image(), r end program chkrandom
Typical output on Windows:
3 0.2110407 6 0.4997412 1 0.1226530 7 0.5719163 8 0.2361415 5 0.1315411 2 0.5468156 4 0.5232784
Typical output on Linux:
1 0.8679414 2 0.8679414 3 0.8679414 4 0.8679414 5 0.8679414 6 0.8679414 7 0.8679414 8 0.8679414
and every once in a while something like this:
1 0.5012199 2 0.5980424 3 0.5012199 4 0.5012199 5 0.5012199 6 0.5012199 7 0.4597191 8 0.5012199
Clearly not the most independent random numbers.
Does anyone know how I can get better results?
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The various suggestions I got led to slightly more variation, but not quite as much as I expected. Here is a typical output from a slightly modified demo program (requiring two random numbers instead of one for each call to random_number):
1 0.6096058 0.3789599
2 0.6165187 0.9890364
3 0.6234315 0.5991130
4 0.6303443 0.2091895
5 0.6372572 0.8192660
6 0.6441700 0.4293426
7 0.6510828 3.9419141E-02
8 0.6579956 0.6494957
It would seem that you need to spend a few more random numbers to get a satisfactory result.
Does anybody have a better suggestion?
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I think you got a typo. Is that not the topic you were referring to
https://software.intel.com/en-us/forums/intel-visual-fortran-compiler-for-windows/topic/808640
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Oops, my apologies - that is indeed the correct reference.
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