full-fledged expressions in themselves.
@menu
-* Booleans:: Boolean values.
+* Boolean Values:: Boolean values.
* Missing Values in Expressions:: Using missing values in expressions.
* Grouping Operators:: ( )
* Arithmetic Operators:: + - * / **
* Order of Operations:: Operator precedence.
@end menu
-@node Booleans, Missing Values in Expressions, Expressions, Expressions
-@section Boolean values
+@node Boolean Values, Missing Values in Expressions, Expressions, Expressions
+@section Boolean Values
@cindex Boolean
@cindex values, Boolean
-There is a third type for arguments and results, the @dfn{Boolean} type,
-which is used to represent true/false conditions. Booleans have only
-three possible values: 0 (false), 1 (true), and system-missing.
-System-missing is neither true nor false.
+Some PSPP operators and expressions work with Boolean values, which
+represent true/false conditions. Booleans have only three possible
+values: 0 (false), 1 (true), and system-missing (unknown).
+System-missing is neither true nor false and indicates that the true
+value is unknown.
-@itemize @bullet
-@item
-A numeric expression that has value 0, 1, or system-missing may be used
-in place of a Boolean. Thus, the expression @code{0 AND 1} is valid
-(although it is always false).
-
-@item
-A numeric expression with any other value will cause an error if it is
-used as a Boolean. So, @code{2 OR 3} is invalid.
-
-@item
-A Boolean expression may not be used in place of a numeric expression.
-Thus, @code{(1>2) + (3<4)} is invalid.
+Boolean-typed operands or function arguments must take on one of these
+three values. Other values are considered false, but cause an error
+when the expression is evaluated.
-@item
Strings and Booleans are not compatible, and neither may be used in
place of the other.
-@end itemize
-@node Missing Values in Expressions, Grouping Operators, Booleans, Expressions
+@node Missing Values in Expressions, Grouping Operators, Boolean Values, Expressions
@section Missing Values in Expressions
String missing values are not treated specially in expressions. Most
descriptions.
User-missing values for numeric variables are always transformed into
-the system-missing value, except inside the arguments to the
-@code{VALUE}, @code{SYSMIS}, and @code{MISSING} functions.
+the system-missing value, except inside the arguments to the
+@code{VALUE} and @code{SYSMIS} functions.
The missing-value functions can be used to precisely control how missing
values are treated in expressions. @xref{Missing Value Functions}, for
@cindex logical intersection
@item @var{a} AND @var{b}
@itemx @var{a} & @var{b}
-True if both @var{a} and @var{b} are true. However, if one argument is
-false and the other is missing, the result is false, not missing. If
+True if both @var{a} and @var{b} are true, false otherwise. If one
+argument is false, the result is false even if the other is missing. If
both arguments are missing, the result is missing.
@cindex @code{OR}
@item @var{a} OR @var{b}
@itemx @var{a} | @var{b}
True if at least one of @var{a} and @var{b} is true. If one argument is
-true and the other is missing, the result is true, not missing. If both
+true, the result is true even if the other argument is missing. If both
arguments are missing, the result is missing.
@cindex @code{NOT}
@cindex logical inversion
@item NOT @var{a}
@itemx ~ @var{a}
-True if @var{a} is false.
+True if @var{a} is false. If the argument is missing, then the result
+is missing.
@end table
@node Relational Operators, Functions, Logical Operators, Expressions
The relational operators take numeric or string arguments and produce Boolean
results.
-Note that, with numeric arguments, PSPP does not make exact
-relational tests. Instead, two numbers are considered to be equal even
-if they differ by a small amount. This amount, @dfn{epsilon}, is
-dependent on the PSPP configuration and determined at compile
-time. (The default value is 0.000000001, or
-@ifinfo
-@code{10**(-9)}.)
-@end ifinfo
-@tex
-$10 ^{-9}$.)
-@end tex
-Use of epsilon allows for round-off errors. Use of epsilon is also
-idiotic, but the author is not a numeric analyst.
-
Strings cannot be compared to numbers. When strings of different
lengths are compared, the shorter string is right-padded with spaces
to match the length of the longer string.
@cindex arccosine
@cindex inverse cosine
-@deftypefn {Function} {} ACOS (@var{number})
-@deftypefnx {Function} {} ARCOS (@var{number})
+@deftypefn {Function} {} ARCOS (@var{number})
Takes the arccosine, in radians, of @var{number}. Results in
-system-missing if @var{number} is not between -1 and 1. Portability:
-none.
+system-missing if @var{number} is not between -1 and 1.
@end deftypefn
@cindex arcsine
Takes the arctangent, in radians, of @var{number}.
@end deftypefn
-@cindex arcsine
-@cindex inverse sine
-@deftypefn {Function} {} ASIN (@var{number})
-Takes the arcsine, in radians, of @var{number}. Results in
-system-missing if @var{number} is not between -1 and 1 inclusive.
-Portability: none.
-@end deftypefn
-
-@cindex arctangent
-@cindex inverse tangent
-@deftypefn {Function} {} ATAN (@var{number})
-Takes the arctangent, in radians, of @var{number}.
-@end deftypefn
-
-@quotation
-@strong{Please note:} Use of the AR* group of inverse trigonometric
-functions is recommended over the A* group because they are more
-portable.
-@end quotation
-
@cindex cosine
@deftypefn {Function} {} COS (@var{angle})
Takes the cosine of @var{angle} which should be in radians.
@cindex values, missing
@cindex functions, missing-value
-Missing-value functions take various types as arguments, returning
-various types of results.
-
-@deftypefn {Function} {} MISSING (@var{variable or expression})
-@var{num} may be a single variable name or an expression. If it is a
-variable name, results in 1 if the variable has a user-missing or
-system-missing value for the current case, 0 otherwise. If it is an
-expression, results in 1 if the expression has the system-missing value,
-0 otherwise.
+Missing-value functions take various numeric arguments and yield
+various types of results. Note that the normal rules of evaluation
+apply within expression arguments to these functions. In particular,
+user-missing values for numeric variables are converted to
+system-missing values.
-@quotation
-@strong{Please note:} If the argument is a string expression other than
-a variable name, MISSING is guaranteed to return 0, because strings do
-not have a system-missing value. Also, when using a numeric expression
-argument, remember that user-missing values are converted to the
-system-missing value in most contexts. Thus, the expressions
-@code{MISSING(VAR1 @var{op} VAR2)} and @code{MISSING(VAR1) OR
-MISSING(VAR2)} are often equivalent, depending on the specific operator
-@var{op} used.
-@end quotation
+@deftypefn {Function} {} MISSING (@var{expr})
+Returns 1 if @var{expr} has the system-missing value, 0 otherwise.
@end deftypefn
@deftypefn {Function} {} NMISS (@var{expr} [, @var{expr}]@dots{})
Each argument must be a numeric expression. Returns the number of
-user- or system-missing values in the list. As a special extension,
+system-missing values in the list. As a special extension,
the syntax @code{@var{var1} TO @var{var2}} may be used to refer to a
range of variables; see @ref{Sets of Variables}, for more details.
@end deftypefn
@deftypefn {Function} {} NVALID (@var{expr} [, @var{expr}]@dots{})
Each argument must be a numeric expression. Returns the number of
-values in the list that are not user- or system-missing. As a special extension,
+values in the list that are not system-missing. As a special extension,
the syntax @code{@var{var1} TO @var{var2}} may be used to refer to a
range of variables; see @ref{Sets of Variables}, for more details.
@end deftypefn
-@deftypefn {Function} {} SYSMIS (@var{variable or expression})
-When given the name of a numeric variable, returns 1 if the value of
-that variable is system-missing. Otherwise, if the value is not
-missing or if it is user-missing, returns 0. If given the name of a
-string variable, always returns 1. If given an expression other than
-a single variable name, results in 1 if the value is system- or
-user-missing, 0 otherwise.
+@deftypefn {Function} {} SYSMIS (@var{expr})
+When @var{expr} is simply the name of a numeric variable, returns 1 if
+the variable has the system-missing value, 0 if it is user-missing or
+not missing. If given @var{expr} takes another form, results in 1 if
+the value is system-missing, 0 otherwise.
@end deftypefn
@deftypefn {Function} {} VALUE (@var{variable})
Prevents the user-missing values of @var{variable} from being
-transformed into system-missing values: If @var{variable} is not
-system- or user-missing, results in the value of @var{variable}. If
-@var{variable} is user-missing, results in the value of @var{variable}
-anyway. If @var{variable} is system-missing, results in system-missing.
+transformed into system-missing values, and always results in the
+actual value of @var{variable}, whether it is user-missing,
+system-missing or not missing at all.
@end deftypefn
@node Pseudo-Random Numbers, Set Membership, Missing Value Functions, Functions
@end deftypefn
@cindex variance
-@deftypefn {Function} {} VAR (@var{number}, @var{number}[, @dots{}])
-Results in the variance of the values of @var{number}. This function
-requires at least two valid arguments to give a non-missing result.
-@end deftypefn
-
@deftypefn {Function} {} VARIANCE (@var{number}, @var{number}[, @dots{}])
Results in the variance of the values of @var{number}. This function
requires at least two valid arguments to give a non-missing result.
-(Use VAR in preference to VARIANCE for reasons of portability.)
@end deftypefn
@node String Functions, Time & Date, Statistical Functions, Functions
@cindex numbers, converting from strings
@cindex strings, converting to numbers
-@deftypefn {Function} {} NUMBER (@var{string})
-Returns the number produced when @var{string} is interpreted according
-to format F@var{x}.0, where @var{x} is the number of characters in
-@var{string}. If @var{string} does not form a proper number,
-system-missing is returned without an error message. Portability: none.
-@end deftypefn
-
@deftypefn {Function} {} NUMBER (@var{string}, @var{format})
Returns the number produced when @var{string} is interpreted according
-to format specifier @var{format}. Only the number of characters in
-@var{string} specified by @var{format} are examined. For example,
-@code{NUMBER("123", F3.0)} and @code{NUMBER("1234", F3.0)} both have
-value 123. If @var{string} does not form a proper number,
-system-missing is returned without an error message.
+to format specifier @var{format}. If the format width @var{w} is less
+than the length of @var{string}, then only the first @var{w}
+characters in @var{string} are used, e.g.@: @code{NUMBER("123", F3.0)}
+and @code{NUMBER("1234", F3.0)} both have value 123. If @var{w} is
+greater than @var{string}'s length, then it is treated as if it were
+right-padded with spaces. If @var{string} is not in the correct
+format for @var{format}, system-missing is returned.
@end deftypefn
@cindex strings, searching backwards
@cindex cross-case function
@cindex function, cross-case
@deftypefn {Function} {} LAG (@var{variable})
+@anchor{LAG}
@var{variable} must be a numeric or string variable name. @code{LAG}
results in the value of that variable for the case before the current
one. In case-selection procedures, @code{LAG} results in the value of
(@samp{=}) and the identifier variable name. The variable must already
have been declared with @cmd{NUMERIC} or another command.
+@cmd{REPEATING DATA} should be the last command given within an
+@cmd{INPUT PROGRAM}. It should not be enclosed within a @cmd{LOOP}
+structure (@pxref{LOOP}). Use @cmd{DATA LIST} before, not after,
+@cmd{REPEATING DATA}.
+
@node WRITE, , REPEATING DATA, Data Input and Output
@section WRITE
@vindex WRITE
variables are combined into a single record. Records with different
values are output in order. Thus, multiple sorted system files are
combined into a single sorted system file based on the value of the BY
-variables.
+variables. The results of the merge become the new active file.
The BY subcommand specifies a list of variables that are used to match
records from each of the system files. Variables specified must exist
IN, FIRST, LAST, and MAP are currently not used.
+@cmd{MATCH FILES} may not be specified following @cmd{TEMPORARY}
+(@pxref{TEMPORARY}) if the active file is used as an input source.
+
@node SAVE, SYSFILE INFO, MATCH FILES, System and Portable Files
@section SAVE
@vindex SAVE
If either DROP or KEEP is specified, the data is read; otherwise it is
not.
+@cmd{MODIFY VARS} may not be specified following @cmd{TEMPORARY}
+(@pxref{TEMPORARY}).
+
@node NUMERIC, PRINT FORMATS, MODIFY VARS, Variable Attributes
@section NUMERIC
@vindex NUMERIC
@cmd{RENAME VARIABLES} takes effect immediately. It does not cause the data
to be read.
+@cmd{RENAME VARIABLES} may not be specified following @cmd{TEMPORARY}
+(@pxref{TEMPORARY}).
+
@node VALUE LABELS, STRING, RENAME VARIABLES, Variable Attributes
@section VALUE LABELS
@vindex VALUE LABELS
(@pxref{LEAVE}) resets the variable's left state. Therefore,
@code{LEAVE} should be specified following @cmd{COMPUTE}, not before.
-COMPUTE is a transformation. It does not cause the active file to be
+@cmd{COMPUTE} is a transformation. It does not cause the active file to be
read.
+When @cmd{COMPUTE} is specified following @cmd{TEMPORARY}
+(@pxref{TEMPORARY}), the @cmd{LAG} function may not be used
+(@pxref{LAG}).
+
@node COUNT, FLIP, COMPUTE, Data Manipulation
@section COUNT
@vindex COUNT
@cmd{FLIP} transposes rows and columns in the active file. It
causes cases to be swapped with variables, and vice versa.
+All variables in the transposed active file are numeric. String
+variables take on the system-missing value in the transposed file.
+
No subcommands are required. The VARIABLES subcommand specifies
variables that will be transformed into cases. Variables not specified
are discarded. By default, all variables are selected for
variable can
be used to recreate the original variable names.
+FLIP honors N OF CASES. It ignores TEMPORARY, so that ``temporary''
+transformations become permanent.
+
@node IF, RECODE, FLIP, Data Manipulation
@section IF
@vindex IF
(@pxref{LEAVE}) resets the variable's left state. Therefore,
@code{LEAVE} should be specified following @cmd{IF}, not before.
+When @cmd{IF} is specified following @cmd{TEMPORARY}
+(@pxref{TEMPORARY}), the @cmd{LAG} function may not be used
+(@pxref{LAG}).
+
@node RECODE, SORT CASES, IF, Data Manipulation
@section RECODE
@vindex RECODE
@cmd{SORT CASES} attempts to sort the entire active file in main memory.
If main memory is exhausted, it falls back to a merge sort algorithm that
-involves writing and reading numerous temporary files. Environment
-variables determine the temporary files' location. The first of
-SPSSTMPDIR, SPSSXTMPDIR, or TMPDIR that is set determines the location.
-Otherwise, if the compiler environment defined P_tmpdir, that is used.
-Otherwise, under Unix-like OSes /tmp is used; under MS-DOS, the first of
-TEMP, TMP, or root on the current drive is used; under other OSes, the
-current directory.
+involves writing and reading numerous temporary files.
+
+@cmd{SORT CASES} may not be specified following TEMPORARY.
@node Data Selection, Conditionals and Looping, Data Manipulation, Top
@chapter Selecting data for analysis
BY is optional but recommended. Cases which have a zero or system- or
user-missing value are excluded from analysis, but not deleted from the
data stream. Cases with other values are analyzed.
+To filter based on a different condition, use
+transformations such as @cmd{COMPUTE} or @cmd{RECODE} to compute a
+filter variable of the required form, then specify that variable on
+@cmd{FILTER}.
@code{FILTER OFF} turns off case filtering.
Filtering takes place immediately before cases pass to a procedure for
analysis. Only one filter variable may be active at a time. Normally,
case filtering continues until it is explicitly turned off with @code{FILTER
-OFF}. However, if @cmd{FILTER} is placed after TEMPORARY, filtering stops
-after execution of the next procedure or procedure-like command.
+OFF}. However, if @cmd{FILTER} is placed after TEMPORARY, it filters only
+the next procedure or procedure-like command.
@node N OF CASES, PROCESS IF, FILTER, Data Selection
@section N OF CASES
processed by procedures. PSPP currently does not make use of
case count estimates.
+When @cmd{N} is specified after @cmd{TEMPORARY}, it affects only
+the next procedure (@pxref{TEMPORARY}).
+
@node PROCESS IF, SAMPLE, N OF CASES, Data Selection
@section PROCESS IF
@vindex PROCESS IF
effects of executing @cmd{TEMPORARY}, then @cmd{SELECT IF}
(@pxref{SELECT IF}).
+The filtering performed by @cmd{PROCESS IF} takes place immediately
+before cases pass to a procedure for analysis. Because @cmd{PROCESS
+IF} affects only a single procedure, its placement relative to
+@cmd{TEMPORARY} is unimportant.
+
@cmd{PROCESS IF} is deprecated. It is included for compatibility with
old command files. New syntax files should use @cmd{SELECT IF} or
@cmd{FILTER} instead.
SAMPLE num1 [FROM num2].
@end display
-@cmd{SAMPLE} is used to randomly sample a proportion of the cases in
-the active file. @cmd{SAMPLE} is temporary, affecting only the next
-procedure, unless that is a data transformation, such as @cmd{SELECT IF}
-or @cmd{RECODE}.
+@cmd{SAMPLE} randomly samples a proportion of the cases in the active
+file. Unless it follows @cmd{TEMPORARY}, it operates as a
+transformation, permanently removing cases from the active file.
The proportion to sample can be expressed as a single number between 0
and 1. If @code{k} is the number specified, and @code{N} is the number
@var{N} cases in the active file.}
@end enumerate
-@cmd{SAMPLE}, @cmd{SELECT IF}, and @code{PROCESS IF} are performed in
+@cmd{SAMPLE} and @cmd{SELECT IF} are performed in
the order specified by the syntax file.
-@cmd{SAMPLE} is ignored before @code{SORT CASES}.
-
@cmd{SAMPLE} is always performed before @code{N OF CASES}, regardless
-of ordering in the syntax file. @xref{N OF CASES}.
+of ordering in the syntax file (@pxref{N OF CASES}).
The same values for @cmd{SAMPLE} may result in different samples. To
obtain the same sample, use the @code{SET} command to set the random
possible. Cases that are deleted early can be processed more
efficiently in time and space.
+When @cmd{SELECT IF} is specified following @cmd{TEMPORARY}
+(@pxref{TEMPORARY}), the @cmd{LAG} function may not be used
+(@pxref{LAG}).
+
@node SPLIT FILE, TEMPORARY, SELECT IF, Data Selection
@section SPLIT FILE
@vindex SPLIT FILE
Specify OFF to disable @cmd{SPLIT FILE} and resume analysis of the
entire active file as a single group of data.
+When @cmd{SPLIT FILE} is specified after @cmd{TEMPORARY}, it affects only
+the next procedure (@pxref{TEMPORARY}).
+
@node TEMPORARY, WEIGHT, SPLIT FILE, Data Selection
@section TEMPORARY
@vindex TEMPORARY
affect only the execution of the next procedure or procedure-like
command. Their effects will not be saved to the active file.
-The only specification is the command name.
+The only specification on @cmd{TEMPORARY} is the command name.
@cmd{TEMPORARY} may not appear within a @cmd{DO IF} or @cmd{LOOP}
-construct. It may
-appear only once between procedures and procedure-like commands.
+construct. It may appear only once between procedures and
+procedure-like commands.
+
+Scratch variables cannot be used following @cmd{TEMPORARY}.
An example may help to clarify:
variable are interpreted as weighting factors of 0. User-missing
values are not treated specially.
+When @cmd{WEIGHT} is specified after @cmd{TEMPORARY}, it affects only
+the next procedure (@pxref{TEMPORARY}).
+
@cmd{WEIGHT} does not cause cases in the active file to be replicated in
memory.
turn, with the same rules applied. If all expressions evaluate to
false, then the @cmd{ELSE} code block is executed, if it is present.
+When @cmd{DO IF} or @cmd{ELSE IF} is specified following @cmd{TEMPORARY}
+(@pxref{TEMPORARY}), the @cmd{LAG} function may not be used
+(@pxref{LAG}).
+
@node DO REPEAT, LOOP, DO IF, Conditionals and Looping
@section DO REPEAT
@vindex DO REPEAT
@cmd{BREAK} also terminates @cmd{LOOP} execution (@pxref{BREAK}).
+When @cmd{LOOP} or @cmd{END LOOP} is specified following @cmd{TEMPORARY}
+(@pxref{TEMPORARY}), the @cmd{LAG} function may not be used
+(@pxref{LAG}).
+
@node Statistics, Utilities, Conditionals and Looping, Top
@chapter Statistics
@node DESCRIPTIVES, FREQUENCIES, Statistics, Statistics
@section DESCRIPTIVES
+@vindex DESCRIPTIVES
@display
DESCRIPTIVES
/VARIABLES=var_list
@node FREQUENCIES, CROSSTABS, DESCRIPTIVES, Statistics
@section FREQUENCIES
+@vindex FREQUENCIES
@display
FREQUENCIES
/VARIABLES=var_list
@node CROSSTABS, T-TEST, FREQUENCIES, Statistics
@section CROSSTABS
+@vindex CROSSTABS
@display
CROSSTABS
/TABLES=var_list BY var_list [BY var_list]@dots{}
@node T-TEST, , CROSSTABS, Statistics
@comment node-name, next, previous, up
-
@section T-TEST
+@vindex T-TEST
@display
T-TEST
/MISSING=@{ANALYSIS,LISTWISE@} @{EXCLUDE,INCLUDE@}
The @cmd{MISSING} subcommand determines the handling of missing
variables.
If INCLUDE is set, then user-missing values are included in the
-calculations.
+calculations, but system-missing values are not.
If EXCLUDE is set, which is the default, user-missing
-values are excluded.
-If LISTWISE is set, then
-the entire case is excluded whenever any value in that case has a
-system-missing or, if INCLUDE is set, user-missing value.
-If ANALYSIS is set, then cases are excluded only where a value used in
-the analysis has a system-missing or, if INCLUDE is set, user-missing value.
+values are excluded as well as system-missing values.
+This is the default.
+
+If LISTWISE is set, then the entire case is excluded from analysis
+whenever any variable specified in the @cmd{/VARIABLES}, @cmd{/PAIRS} or
+@cmd{/GROUPS} subcommands contains a missing value.
+If ANALYSIS is set, then missing values are excluded only in the analysis for
+which they would be needed. This is the default.
@menu
`Groups' mode.
This mode is used to test whether two groups of values have the
same population mean.
+In this mode, you must also use the @cmd{/VARIABLES} subcommand to
+tell PSPP the dependent variables you wish to test.
+
The variable given in the @cmd{GROUPS} subcommand is the independent
variable which determines to which group the samples belong.
The values in parentheses are the specific values of the independent
variable for each group.
-In this mode, you must also use the @cmd{/VARIABLES} subcommand to
-tell PSPP the dependent variables you wish to test.
+If the parentheses are omitted and no values are given, the default values
+of 1.0 and 2.0 are assumed.
+
+If the independent variable is numeric,
+it is acceptable to specify only one value inside the parentheses.
+If you do this, cases where the independent variable is
+less than or equal to this value belong to the first group, and cases
+greater than this value belong to the second group.
+When using this form of the @cmd{GROUPS} subcommand, missing values in
+the independent variable are excluded on a listwise basis, regardless
+of whether @cmd{/MISSING=LISTWISE} was specified.
+
@node Paired Samples Mode, , Independent Samples Mode, T-TEST
@comment node-name, next, previous, up
* INCLUDE:: Include a file within the current one.
* QUIT:: Terminate the PSPP session.
* SET:: Adjust PSPP runtime parameters.
+* SHOW:: Display runtime parameters.
* SUBTITLE:: Provide a document subtitle.
* TITLE:: Provide a document title.
@end menu
This command is not valid within a command file.
-@node SET, SUBTITLE, QUIT, Utilities
+@node SET, SHOW, QUIT, Utilities
@section SET
@vindex SET
overwrite files, for instance) but it is an improvement.
@end table
-@node SUBTITLE, TITLE, SET, Utilities
+@node SHOW, SUBTITLE, SET, Utilities
+@comment node-name, next, previous, up
+@section SHOW
+@vindex SHOW
+
+@display
+SHOW
+ /@var{subcommand}
+
+@end display
+
+@cmd{SHOW} can be used to display the current state of PSPP's
+execution parameters. All of the parameters which can be changed
+using @code{SET} @xref{SET}, can be examined using @cmd{SHOW}, by
+using a subcommand with the same name.
+In addition, @code{SHOW} supports the following subcommands:
+
+@table @code
+@item WARRANTY
+Show details of the lack of warranty for PSPP.
+@item COPYING
+Display the terms of PSPP's copyright licence @ref{License}.
+@end table
+
+
+
+@node SUBTITLE, TITLE, SHOW, Utilities
@section SUBTITLE
@vindex SUBTITLE
projects / pspp / blobdiff