Re: [ccp4bb]: Error running FFT in alpha

["C.C.Ballard" <C.C.Ballard@dl.ac.uk>]

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Miguel,

first off, what Alpha machine are you using.  Previously we have had
reports of problems using fft on the XP1000, divide by zero in that case.
That seemed to have been caused by various arrays being overwritten,
although the problem was not fully tracked down.

Several solutions were found though.

1.  use FFTBIG.  This worked.  It uses dynamic memory allocation.
2.  increase the size of the working array, X.  Set IDUM to 1000000.  This
    will work if the problem arises in the sorting routines by bypassing
    the multiple passes.
3.  turning off optimization seemed to also cure the problem.  Could be
    that it arose due code reordering.  Warning: this leads to a large
    performance hit.

Hope these suggestions help.

Charles Ballard

ps- anyone using a new Alpha have any further information?