MTZTONA4 (CCP4: Supported Program)
NAME
mtztona4, na4tomtz
- interconvert MTZ reflection file and ASCII format.
SYNOPSIS
mtztona4 hklin
foo.mtz
hklout
foo.na4
na4tomtz hklin
foo.na4
hklout
foo.mtz
DESCRIPTION
The
mtztona4
and
na4tomtz
programs interconvert binary and ASCII reflection files for transport
of reflection data between machine types.
No input is required, other than the command line with file
assignments.
mtztona4 can optionally produce a run-length-encoded (RLE) format that
is more compact than the original NA4 format; however the old version
of na4tomtz cannot read the new format (it will echo the input data to
standard output without converting it). Only the current version of
na4tomtz can convert the RLE format back to MTZ (of course the current
na4tomtz can also convert the old NA4 format to MTZ).
To select the RLE option in mtztona4, define the environment variable:
CCP4_RLENA4 (na4tomtz does not require this to be defined as it detects
automatically NA4 or RLE format).
N.B. With the current version of the CCP4 library there is little
need for the NA4 format since MTZ files may be read transparently on
different architectures (though it is useful for sending data by e-mail).
DETAILS OF OPERATION
mtztona4
gets index values from the ranges for each column
for REAL to CHARACTER*4 inter-conversion, with REALs converted
to INTEGER in the range 0 to 2**24-1. (Negative numbers are
converted to 2's complement.) Then the INTEGER value is converted to
CHARACTER*4 using a 64-character translation table.
After an ASCII readable header is output to HKLOUT
the reflection data are stored as characters. A sample of an output
file is given below:
u000200000002Kk0eU0000000000000000000000000000000000
u000200040005ts0B000000000007hc07w000000000000000000
u000200080003Kk0K80000000000000000000000000000000000
If the MTZ file is converted so that unmeasured items are flagged (F's with
zero sigmas changed to NaN's), and the CCP4_RLENA4 option is activated, the
same piece of output looks like this:
u%02*22Kk0eU%.7
u%02%04%05ts0B%0.17hc07w%.3
u%02%08%03Kk0K8%.7
ACCURACY
The errors are in relation to the largest absolute value in the column,
so in general you will have an error of 0.01 relative to about 90000
or 1 in 10**8, which is not likely to cause any problems.
FILE SIZES
The run-length-encoded format gives a somewhat smaller file than either
the original MTZ file or the old NA4 file, for example (sizes in bytes):
-rw-r--r-- 1 programs 169684 Mar 2 13:14 toxd.mtz
-rw-r--r-- 1 programs 172130 Mar 3 12:12 toxd.na4
-rw-r--r-- 1 programs 110437 Mar 3 12:14 toxd_flag.rle
EXAMPLE
mtztona4 hklin toxd hklout toxd.na4
na4tomtz hklin toxd.na4 hklout toxd
AUTHOR
Ian Tickle, Birkbeck College
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