16.4 MATRIX

MATRIX.
… _matrix commands_ …
END MATRIX.

The following basic matrix commands are supported:

COMPUTE _variable_[(_index_[,_index_])]=_expression_.
CALL _procedure_(_argument_ , …).
PRINT [_expression_]
      [/FORMAT=_format_]
      [/TITLE=_title_]
      [/SPACE={NEWPAGE _|_ _n_}]
      [{/RLABELS=_string_ … _|_ /RNAMES=_expression_}]
      [{/CLABELS=_string_ … _|_ /CNAMES=_expression_}].

The following matrix commands offer support for flow control:

DO IF _expression_.
  … _matrix commands_ …
[ELSE IF _expression_.
  … _matrix commands_ …]…
[ELSE
  … _matrix commands_ …]
END IF.

LOOP [_var_ =_first_ TO _last_ [BY _step_]] [IF _expression_].
  … _matrix commands_ …
END LOOP [IF _expression_].

BREAK.

The following matrix commands support matrix input and output:

READ _variable_[(_index_[,_index_])]
     [/FILE=_file_]
     /FIELD=_first_ TO _last_ [BY _width_]
     [/FORMAT=_format_]
     [/SIZE=_expression_]
     [/MODE={RECTANGULAR _|_ SYMMETRIC}]
     [/REREAD].
WRITE _expression_
      [/OUTFILE=_file_]
      /FIELD=_first_ TO _last_ [BY _width_]
      [/MODE={RECTANGULAR _|_ TRIANGULAR}]
      [/HOLD]
      [/FORMAT=_format_].
GET _variable_[(_index_[,_index_])]
    [/FILE={_file_ _|_ *}]
    [/VARIABLES=_variable_ …]
    [/NAMES=_expression_]
    [/MISSING={ACCEPT _|_ OMIT _|_ _number_}]
    [/SYSMIS={OMIT _|_ _number_}].
SAVE _expression_
     [/OUTFILE={_file_ _|_ *}]
     [/VARIABLES=_variable_ …]
     [/NAMES=_expression_]
     [/STRINGS=_variable_ …].
MGET [/FILE=_file_]
     [/TYPE={COV _|_ CORR _|_ MEAN _|_ STDDEV _|_ N _|_ COUNT}].
MSAVE _expression_
      /TYPE={COV _|_ CORR _|_ MEAN _|_ STDDEV _|_ N _|_ COUNT}
      [/OUTFILE=_file_]
      [/VARIABLES=_variable_ …]
      [/SNAMES=_variable_ …]
      [/SPLIT=_expression_]
      [/FNAMES=_variable_ …]
      [/FACTOR=_expression_].

The following matrix commands provide additional support:

DISPLAY [{DICTIONARY _|_ STATUS}].
RELEASE _variable_ ….

MATRIX and END MATRIX enclose a special PSPP sub-language, called the matrix language. The matrix language does not require an active dataset to be defined and only a few of the matrix language commands work with any datasets that are defined. Each instance of MATRIX…END MATRIX is a separate program whose state is independent of any instance, so that variables declared within a matrix program are forgotten at its end.

The matrix language works with matrices, where a matrix is a rectangular array of real numbers. An n ×m matrix has n rows and m columns. Some special cases are important: a n ×1 matrix is a column vector , a 1× n is a row vector , and a 1×1 matrix is a scalar.

The matrix language also has limited support for matrices that contain 8-byte strings instead of numbers. Strings longer than 8 bytes are truncated, and shorter strings are padded with spaces. String matrices are mainly useful for labeling rows and columns when printing numerical matrices with the MATRIX PRINT command. Arithmetic operations on string matrices will not produce useful results. The user should not mix strings and numbers within a matrix.

The matrix language does not work with cases. A variable in the matrix language represents a single matrix.

The matrix language does not support missing values.

MATRIX is a procedure, so it cannot be enclosed inside DO IF, LOOP, etc.

Macros may be used within a matrix program, and macros may expand to include entire matrix programs. The DEFINE command may not appear within a matrix program. See DEFINE, for more information about macros.

The following sections describe the details of the matrix language: first, the syntax of matrix expressions, then each of the supported commands. The COMMENT command (see COMMENT) is also supported.

• Matrix Expressions
• Matrix Functions
• The COMPUTE Command
• The CALL Command
• The PRINT Command
• The DO IF Command
• The LOOP and BREAK Commands
• The READ and WRITE Commands
• The GET Command
• The SAVE Command
• The MGET Command
• The MSAVE Command
• The DISPLAY Command
• The RELEASE Command