The MAD-X program, which is used for the design of the LHC optics and other accelerators, is presently modified to be used as an on-line simulation tool. In this note we describe additional features developped for MAD-X to read and write the data structures used in the LHC Application Software project

Herr, Werner

Schmidt, F

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EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCHCERN – AB DEPARTMENTWerner.Herr@cern.ch AB-Note-2006-043 (ABP)Using SDDS data sets with MAD-XW. Herr and F. SchmidtAB Department, CERN, 1211-Geneva 23AbstractThe MAD-X program, which is used for the design of the LHC optics and other acceler-ators, is presently modified to be used as an on-line simulation tool. In this note we describeadditional features developped for MAD-X to read and write the data structures used in theLHC Application Software project.Geneva, Switzerland6 November 20061 SDDS data sets1.1 Why SDDS in MAD-X ?The Self Describing Data Set (SDDS) [1] was developed at the Advanced Photon Source (APS) at Ar-gonne National Laboratory for use in the simulation and operation of accelerators. It was adopted as adata structure in the LHC Application Software project [2].The MAD-X program [3], which is used for the design of the LHC optics and other accelerators, ispresently modified to be used as an on-line simulation tool within the LHC control system. The mainpurpose is to have an on-line tool available for modelling and simulation of the LHC and to evaluateforeseen manipulations of the beams. However, it is not foreseen that it is used to directly control thebeams, i.e. change settings of the hardware.This MAD-XO (MAD-X On-line) will not be an integral part of the standard MAD-X program, butrather an extension and therefore a customized version to account for the needs of the control and mod-elling of the LHC.A major issue is therefore an efficient communication between MAD-X and the control system (appli-cation !) software [4]. The standard format for input and output for MAD-X are files in the TFS (TableFiling System) style. To that purpose it was decided to provide a data interface between TFS and SDDS.The following tools are now available:  Stand alone conversion between TFS and SDDS files.  Stand alone template to access SDDS files.  Read SDDS files and internal conversion to MAD-X tables.  Conversion from MAD-X tables and write SDDS files.Since MAD-X can write and read TFS files, it can be used as a converter.1.2 SDDS protocolA more complete description of the SDDS protocol and file structure is given in [5]. To make it selfdescribing, all data elements are preceded by a definition of the data, including type, size and description.This information is stored in a header.The header also includes so-called 		 which can be used to store additional information suchas time stamps, versions, energy etc.The data elements are stored in form of tabulated data (columns) or arrays. Both, binary and ASCII filescan be handled.1.3 MAD-X and SDDS data setsThe MAD-X program [3] uses its own self describing data structure, the so-called TABLE structure. Allinformation is stored internally in this 	 data set and can be written to file or read from file usingstandard MAD-X commands. The main features and use of this data sets are:  Dynamically defined at execution time.  Simple format for archiving in files (tables).  Communication of data from MAD-X.  Communication of data to MAD-X.The format of the TFS files allow easy processing or manipulation of the input and output data. Thegraphical presentation of data can be provided by generic programs like ﬁﬀﬂ which can read andinterpret these files. TFS files are always in ASCII format, a binary version is not foreseen. Both, TFS2MAD-X SDDSone dimensional data column 1-D arraytwo dimensional data n/a 2-D arraytabular data column columnadditional information header parameterTable 1: MAD-X TABLE and SDDS comparison.and SDDS formats are not relocatable.For the more complex structure of SDDS a powerful toolkit is available [5] to manipulate the files or toanalyze the data.However, there are a few differences between TABLE and SDDS and in Tab.1 below we show a shortcomparision which also defines the different naming conventions. From Tab. 1 it can be seen that notall data structures have an equivalent counterpart in both representations. Therefore only data elementswhich can be handled in the TABLE structure are treated.2 Implementation in MAD-XFor handling SDDS data sets, a new module has been written for MAD-X. To allow the input and outputof SDDS files in MAD-X, the available SDDS source was used [6]. This ensures full compatibility andallows the use of the SDDS toolkit. The files (binary or ASCII) are read and an internal MAD-X TABLEstructure is created to hold the data and other information. This table can be used internally like anyother MAD-X table.Data elements from a SDDS data set which cannot be implemented in a MAD-X table are ignored oninput. The SDDS parameters are stored as ”headers” in the MAD-X table. If the table is dumped to afile with     	  ﬁ	 , the headers are conserved.2.1 Input and output commandsThe read command has the following form:SDDSIN, FILE=    	 	 ,TABLE=    	 	 ;The internal table has the name   	 	 , the default name is  .The command for writing a SDDS table has the form:SDDSOUT, FILE=     ﬁ	 	 ,TABLE=    ﬁ	 	 ;Any internal table can be written as a SDDS data set.32.2 Selective input and outputThe input command can be used together with a SELECT command which allows to read and store onlythe selected arrays. The command acts on the array names and therefore only  	 can be usedfor the selection.SELECT,FLAG=SDDS,CLEAR;SELECT,FLAG=SDDS,PATTERN= ....;SDDSIN, FILE=    	 	 ,TABLE=    	 	 ;This can be used to avoid problems with incompatible data elements. Regular expressions are allowedas a pattern.It is possible to select only certain columns of an internal table for output on a SDDS data set. Thisis done with a command of the form:SELECT,FLAG=    	 	 ,CLEAR;SELECT,FLAG=    	 	 ,COLUMN= ....;SDDSOUT, FILE=     ﬁ	 	 ,TABLE=    ﬁ	 	 ;Please note that the keyword 	 is used for the selection since it refers to a TFS table. Aselection of rows of the table is not foreseen.3 Comments and pitfalls3.1 Available data typesThe possible data types are those which can be used in MAD-X tables, i.e. ﬀ   	 , ﬀ  and     data. All single precision floating point data or short integers are converted1.The implementation required a few changes to the MAD-X core, but are invisible to the user. Thesemodifications will be propagated into the standard MAD-X program.3.2 Naming conventionsThe names of SDDS arrays and parameters are used for the TFS columns and headers respectively.This is the case for conversion in both directions. The selection with regular expressions using the 	 option is case sensitive. However, internally all names of headers and columns are usedas lower case and converted during the input of SDDS or TFS data sets.When TFS tables are written, they are converted to upper case.Therefore one should note that:  Input files are accepted with both, lower and upper case names (take care with  	 selec-tion).  After conversion all names on output files (SDDS or TFS) are uppercase.  Lower and upper case must not be used to distinguish arrays (columns) with otherwise identicalnames.  Parameters (headers) can have names identical to arrays (columns) since they are treated separately.1Internally long integers are also stored as double precision floating point number.44 Examples for the use of SDDS files4.1 Reading SDDS filesTITLE, s=’MAD-X test’;option,-echo;sddsin,file="cngs-test.sdds",table="sdds_tfs";write, table="sdds_tfs",file="tfs1";4.2 Reading SDDS files with array selectionTITLE, s=’MAD-X test’;option,-echo;select,flag=sdds,clear;select,flag=sdds,pattern="ˆb.*";select,flag=sdds,pattern="ˆd.*";! convert: read SDDS and write TFS filessddsin,file="cngs-test.sdds",table="sdds_tfs";write, table="sdds_tfs",file="tfs1";4.3 Writing SDDS filesTITLE, s=’MAD-X test’;option,-echo;write, table="newtab",file="tfs3";sddsout,table="newtab",file="myOUTfile";4.4 Writing SDDS files from Twiss tableTITLE, s=’MAD-X test’;option,-echo;call file="TT41_010606_9.seq";option,-echo,-info;BEAM ENERGY=400.0,particle=proton;use, period=tt41;Select,flag=twiss,column=name,s,x,px,y,py,betx,bety,dx;TWISS,file=tt41_06_9.out;! write Twiss data as SDDS, use default table name "twiss"sddsout,file="myOUTfile",table="twiss";The command sequence below is equivalent: an existing TFS file is read into memory via the 	ﬂ 	command and stored in the named table  	    . This table is dumped on a SDDS file again as above.TITLE, s=’MAD-X test’;option,-echo;readtable,file="tt41_06_9.out",table="newtab";sddsout,file="myOUTfile2",table="newtab";References[1] Operations and Analysis Software Documentation,http://aps.anl.gov/Accelerator Systems Division/Operations Analysis/oagSoftware.shtml5[2] http://slwww.cern.ch/pcrops/releaseinfo/pcropsdist/accsoft/sdds/accsoft-sdds-core/PRO/build/docs/api/[3] The MAD-X Home Page, version April 2005,http://cern.ch/frank.schmidt/Xdoc/mad-X.html.[4] http://ab-project-lsa.web.cern.ch/ab-project-lsa/[5] M. Borland; Getting Started with SDDS,http://aps.anl.gov/Accelerator Systems Division/Operations Analysis/manuals/GettingStartedWithSDDS/HTML/GettingStartedWithSDDS.html[6] M. Borland and R. Soliday; Applications Programmer’s Guide for SDDS Version 1.5, AdvancedPhoton Source, Argonne National Laboratory, U.S.A., May 2006.6

Using SDDS data sets with MAD-X

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