If somebody is going to send these files by email, please send one to me too. Thanks in advance. I actually prefer to get a MTZ file because the miller indices would serve as good clues for understanding the encodings. Even the first 1024 bytes of an MTZ would do (data array starts at byte 80 in MTZ).
In my life I had only seen ieee754. According to what I can find, VAX has an exponent bias of 128 (ieee754 uses 127). Then it seems to me that when converting from vax to ieee a division of 2 is involved. However all procedures I have seen use a division of 4, which is quite puzzling to me. A real data file containing meaningful numbers (eg., HKL indices) would be very helpful. Thanks in advance. Zhijie > On Nov 13, 2018, at 2:21 PM, Johan Hattne <hat...@ucla.edu> wrote: > > Related by not exactly on topic: would anybody on the list be able to share > old map files (not MTZ:s) with Convex, Cray, Fujitsu, or VAX reals/strings? > I’d be interested to see what those files actually look(ed) like. > > // Best wishes; Johan > >> On Nov 9, 2018, at 18:38, Zhijie Li <zhijie...@utoronto.ca> wrote: >> >> Hi all, >> >> On linux there are a few good GUI HEX editors. Here I’d like to recommend >> BLESS, which conveniently displays all possible numerical interpretations of >> the four bytes under cursor. It also allows the user to switch between big >> endian or little endian through a checkbox. Unfortunately all floats are >> assumed to be IEEE754, therefore VAX floats won’t be interpreted correctly. >> ( The simplest way to convert vax to ieee float would be to write a little >> program to do some bit operations. I’d be happy to take that as my weekend >> project) >> >> >> BTW, along the line of space efficiency, I can’t help noticing that the >> miller indices are saved as float32 in mtz, as all other numbers in mtz. >> This certainly have made mtz format a beautiful homogeneous data format ;). >> In this particular case, if we have doubts about the reliability of the >> machine stamp, trying to restore the miller indices would be a good way to >> test hypotheses. >> >> Zhijie >> >>> On Nov 9, 2018, at 9:04 PM, James Holton >>> <0000270165b9f4cf-dmarc-requ...@jiscmail.ac.uk> wrote: >>> >>> As a beamline scientist I must say I am glad that diffraction image data is >>> not usually stored as ASCII text. In fact, I am slowly warming to the idea >>> of storing it as not just binary, but compressed formats. Problem, I'm >>> sure will be that it won't be long before we forget how to decompress >>> them, as most of the algorithms we are using aren't all that widespread. >>> Probably around the same time future generations will curse us for using >>> ASCII instead of unicode, which is a 16-bit standard. I'm sure we will be >>> reviled for limiting ourselves so, just to save a factor of two in disk >>> space. >>> In situations like this I always use the unix "od" command. It makes >>> everything "human readable" by converting the bytes into strings you can >>> read. Then it is just a matter of figuring out what the bytes are. >>> Unfortunately, "od" only decodes floats on the native platform, so if the >>> mtz is from another platform (Windows vs Linux, for example), then you >>> might need to do some swapping. Thus far, I have encountered files that >>> require one of a few swapping strategies in order to make them work: >>> >>> 1 2 3 4 - no swapping >>> >>> 4 3 2 1 - reverse all bytes >>> >>> 3 4 1 2 - swap words and swap bytes within the words >>> 2 1 4 3 - reverse of previous >>> >>> 2-1 1 4 3 - same as last, but if not all zero, decrement byte #2 before >>> swapping >>> 3 4 1 2+1 - same as 3412, but if not all zero increment byte #2 before >>> swapping >>> I'm sure there are other combinations, but the oldest MTZ I have is only >>> from 1996. >>> >>> -James Holton >>> MAD Scientist >>> >>> >>>> On 11/9/2018 4:47 AM, Eleanor Dodson wrote: >>>> Anyone any idea what to do about this?? Created in 1992!! >>>> Seems unreadable.. >>>> >>>> No CTYP lines input for file: 1 >>>> Indices output even if all data items flagged "missing" >>>> Warning, NOT all LABOUT data lines given >>>> Warning: Machine stamp corrupted? Assuming native format. >>>>>>>>>> CCP4 library signal library_file:End of File (Error) >>>> >>>> >>>> To unsubscribe from the CCP4BB list, click the following link: >>>> https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 >>>> >>> >>> >>> To unsubscribe from the CCP4BB list, click the following link: >>> https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 >>> >> >> To unsubscribe from the CCP4BB list, click the following link: >> https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 >> > > Research Specialist @ Gonen Lab > ____________________________________________________ > UCLA * 615 Charles E. Young Drive South > BSRB #347 * Los Angeles, CA 90095 > > ######################################################################## > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1
