7.57 rpn_load

• type: action/setup command.
• function: load data from SDDS file into RPN variables.
• Command syntax, including use of equations and subcommands, is discussed in 7.2.

This command is used to facilitate multi-stage optimization runs by allowing convenient loading of data from SDDS files into RPN variables. For example, one may match the final Twiss parameters of a lattice to the parameters stored in an SDDS file from a different run.

• tag — Option string that will be pre-pended to the names of all the numerical columns in the file in order to create RPN variable names. E.g., if the input file was from the twiss_output command and tag = tw1 was given, then RPN variables tw1.betax, tw1.alphax, etc. would be used. N.B.: If the tag is blank, then nothing is appended to the names from the file. This can be dangerous since the names may conflict with the names of other variables!
• filename — The (incomplete) name of the SDDS file from which to read data. By default, data is taken from all columns from the last row of the last page of the file. This default behavior can be altered using one or more of the following parameters:
  • match_column — The name of a string column to use in selecting the row from which data will be taken.
  • match_column_value — The value that the column named by match_column must have to be selected from the file. By default, the last row with a matching value is used.
  • matching_row_number — If a nonnegative value is given, then the matching_row_number^th matching row is selected (0 is the first row, 1 the second, etc). Otherwise, the last match row is used. Ignored if match_column is not given.
  • match_parameter — The name of a string parameter to use in selecting the page from which data will be taken.
  • match_parameter_value — The value that the parameter named by match_parameter must have to be selected from the file. By default, the last page with a matching value is used.
  • use_row — If nonnegative, specifies the row number to use, starting at 0 for the first row. Ignored if match_column is given.
  • use_page — If nonnegative, specifies the page number to use, starting at 1 for the first page. Takes precedence over \match_parameter if both are given.
  • load_parameters — If nonzero, specifies loading the SDDS parameter data rather than the column data.