Cristina, I looked a little further into the memory error. I had been using an older version of phast on the pc, which ran your problem. However, when I used the RC2 version, it failed on Windows XP with the same error message that you got. I think the difference between XP and 98 is in the memory management performed by the operating system. Neither one is right or wrong, just different. With the way phast was written, XP ended up fragmenting the memory, so there was no contiguous memory large enough to handle phast's request for a large chunk of memory, even though there was plenty of memory available (just in smaller pieces). 98 apparently allocates the memory differently and for this program and problem, it provides larger chunks of contiguous memory. Phast needed a set of contiguous memory to store the ion exchange information (for example), but it was inefficient in the way it did it. It simply made enough space for the first cell, stored the first cell (which involved asking for some more space), then made enough space for two cells, stored the second cell, and so on. I think that process of always needing bigger chunks of memory and allocating some memory to store each cell was what caused the problem. Memory was cut up into small noncontiguous segments. I have rewritten that section of the code so that phast allocates enough space for all the ion exchange information initially and then stores each cell. Hopefully this approach will not fragment the memory so badly and will also be more efficient by not having to continually reallocate space for the expanding array of ion exchange data. Sorry I did not figure this out sooner, but it is a pretty subtle problem. Here is a new version of phast and phastinput that should run equally well on XP and 98. There have been some enhancements since RC2 (-mask, 2 transverse dispersivities, PRINT_LOCATIONS, probably a couple others), but I think the new version should run older input files. If you are running large problems, you may want to consider running the parallel version of phast. You need either a dual processor machine or a well-connected network (probably 100 Mbit/s or better) of single or dual processor machines. You also need a package for MPI (Message Passing Interface); there are commercial packages or MPICH is public domain, which runs on pc's. We don't provide any support for getting MPI functioning, but if you do, you should be able to run the parallel version, which speeds up the chemistry calculations roughly proportionately to the number and speed of processors used. One drawback is that the memory requirements are the same for each processor. David (See attached file: phastinput.exe)(See attached file: phast.exe)(See attached file: user.transport.pdf) David David Parkhurst (dlpark@xxxxxxxx) U.S. Geological Survey Box 25046, MS 413 Denver Federal Center Denver, CO 80225 Project web page: https://wwwbrr.cr.usgs.gov/projects/GWC_coupled
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