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Re: Memory for large arrays in cygwin/g77

Dave Korn wrote:
From: cygwin-owner On Behalf Of Mark Hadfield
Sent: 10 January 2005 21:18

Is there a cure that would allow a simple-minded, grey-haired Fortran programmer like me to rely on Cygwin g77 (or gfortran) for moderate-sized computational tasks?

LOL, I love the subtle sense of understatement you fortran guys use to describe handling arrays of hundreds of millions of elements :)

Though I am prone to occasionally employing subtlety, understatement and irony for effect in forums like this, my reference to moderate-sized computational tasks in this connection was not such an occasion.

I run an ocean hydrodynamic model (ROMS) with domain size around 200 x 200 x 30, sometimes larger. For the serious computations I use a Cray T3E, but for smaller stuff I use my Windows desktop machine or one of several Linux x86 machines with 1 or 2 CPUs, whatever I can get my hands on. For me a moderate-size simulation needs 256-512 MiB of memory. (If they're much larger than that, then they run too slow on the PC, so the limits associated with 32-bit addressing are not a major issue for me yet, but they will be in a few years' time.)

> Anyway, the simple answer appears to be "Use g95 instead",
> doesn't it?

Bascally, yes. I've been using g95 recently and have found it reliable and able to handle moderate-sized simulations, though execution is rather slow. However I did get a "MapViewOfFileEx" error recently with g95 on an old version of ROMS. That's not a show-stopper, as I seldom use that version any more, but it's a little worrying...

-- Mark Hadfield "Ka puwaha te tai nei, Hoea tatou" National Institute for Water and Atmospheric Research (NIWA)

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