X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=doc%2Fexpressions.texi;h=65778d0424188c0db3fc39d3b9183491e6583643;hb=refs%2Fbuilds%2F20120402030503%2Fpspp;hp=32ace6c2dca2763ce716388c097d5e996f84650c;hpb=9a331fe64eb814ae5c1322e21717a04fb254bf65;p=pspp diff --git a/doc/expressions.texi b/doc/expressions.texi index 32ace6c2dc..65778d0424 100644 --- a/doc/expressions.texi +++ b/doc/expressions.texi @@ -3,7 +3,7 @@ @cindex expressions, mathematical @cindex mathematical expressions -Expressions share a common syntax each place they appear in PSPP +Expressions share a common syntax each place they appear in @pspp{} commands. Expressions are made up of @dfn{operands}, which can be numbers, strings, or variable names, separated by @dfn{operators}. There are five types of operators: grouping, arithmetic, logical, @@ -15,14 +15,14 @@ strings or numbers as operands. With few exceptions, operands may be full-fledged expressions in themselves. @menu -* Boolean Values:: Boolean values. -* Missing Values in Expressions:: Using missing values in expressions. -* Grouping Operators:: parentheses -* Arithmetic Operators:: add sub mul div pow -* Logical Operators:: AND NOT OR -* Relational Operators:: EQ GE GT LE LT NE -* Functions:: More-sophisticated operators. -* Order of Operations:: Operator precedence. +* Boolean Values:: Boolean values +* Missing Values in Expressions:: Using missing values in expressions +* Grouping Operators:: parentheses +* Arithmetic Operators:: add sub mul div pow +* Logical Operators:: AND NOT OR +* Relational Operators:: EQ GE GT LE LT NE +* Functions:: More-sophisticated operators +* Order of Operations:: Operator precedence @end menu @node Boolean Values @@ -30,7 +30,7 @@ full-fledged expressions in themselves. @cindex Boolean @cindex values, Boolean -Some PSPP operators and expressions work with Boolean values, which +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 @@ -238,7 +238,7 @@ True if @var{a} is not equal to @var{b}. @cindex @code{(} @cindex @code{)} @cindex names, of functions -PSPP functions provide mathematical abilities above and beyond +@pspp{} functions provide mathematical abilities above and beyond those possible using simple operators. Functions have a common syntax: each is composed of a function name followed by a left parenthesis, one or more arguments, and a right parenthesis. @@ -259,7 +259,7 @@ The sections below describe each function in detail. * Statistical Functions:: CFVAR MAX MEAN MIN SD SUM VARIANCE * String Functions:: CONCAT INDEX LENGTH LOWER LPAD LTRIM NUMBER RINDEX RPAD RTRIM STRING SUBSTR UPCASE -* Time & Date:: CTIME.xxx DATE.xxx TIME.xxx XDATE.xxx +* Time and Date:: CTIME.xxx DATE.xxx TIME.xxx XDATE.xxx DATEDIFF DATESUM * Miscellaneous Functions:: LAG YRMODA VALUELABEL * Statistical Distribution Functions:: PDF CDF SIG IDF RV NPDF NCDF @@ -349,7 +349,7 @@ results. @deftypefnx {Function} {} ACOS (@var{number}) Takes the arccosine, in radians, of @var{number}. Results in system-missing if @var{number} is not between -1 and 1 inclusive. -This function is a PSPP extension. +This function is a @pspp{} extension. @end deftypefn @cindex arcsine @@ -691,34 +691,34 @@ has value @code{"cd"}; @code{SUBSTR("nonsense", 4, 10)} has the value Returns @var{string}, changing lowercase letters to uppercase letters. @end deftypefn -@node Time & Date +@node Time and Date @subsection Time & Date Functions @cindex functions, time & date @cindex times @cindex dates @cindex dates, valid -For compatibility, PSPP considers dates before 15 Oct 1582 invalid. +For compatibility, @pspp{} considers dates before 15 Oct 1582 invalid. Most time and date functions will not accept earlier dates. @menu -* Time & Date Concepts:: How times & dates are defined and represented +* Time and Date Concepts:: How times & dates are defined and represented * Time Construction:: TIME.@{DAYS HMS@} * Time Extraction:: CTIME.@{DAYS HOURS MINUTES SECONDS@} * Date Construction:: DATE.@{DMY MDY MOYR QYR WKYR YRDAY@} * Date Extraction:: XDATE.@{DATE HOUR JDAY MDAY MINUTE MONTH QUARTER SECOND TDAY TIME WEEK WKDAY YEAR@} -* Time & Date Arithmetic:: DATEDIFF DATESUM +* Time and Date Arithmetic:: DATEDIFF DATESUM @end menu -@node Time & Date Concepts +@node Time and Date Concepts @subsubsection How times & dates are defined and represented @cindex time, concepts @cindex time, intervals -Times and dates are handled by PSPP as single numbers. A -@dfn{time} is an interval. PSPP measures times in seconds. +Times and dates are handled by @pspp{} as single numbers. A +@dfn{time} is an interval. @pspp{} measures times in seconds. Thus, the following intervals correspond with the numeric values given: @example @@ -731,9 +731,9 @@ Thus, the following intervals correspond with the numeric values given: @cindex dates, concepts @cindex time, instants of A @dfn{date}, on the other hand, is a particular instant in the past -or the future. PSPP represents a date as a number of seconds since +or the future. @pspp{} represents a date as a number of seconds since midnight preceding 14 Oct 1582. Because midnight preceding the dates -given below correspond with the numeric PSPP dates given: +given below correspond with the numeric @pspp{} dates given: @example 15 Oct 1582 86,400 @@ -773,7 +773,7 @@ vice versa. @cindex examination, of times @cindex time, lengths of -These functions take numeric arguments in PSPP time format and +These functions take numeric arguments in @pspp{} time format and give numeric results. @cindex days @@ -886,18 +886,18 @@ Results in a date value corresponding to the day @cindex date examination @cindex arguments, of date extraction functions -These functions take numeric arguments in PSPP date or time +These functions take numeric arguments in @pspp{} date or time format and give numeric results. These names are used for arguments: @table @var @item date -A numeric value in PSPP date format. +A numeric value in @pspp{} date format. @item time -A numeric value in PSPP time format. +A numeric value in @pspp{} time format. @item time-or-date -A numeric value in PSPP time or date format. +A numeric value in @pspp{} time or date format. @end table @cindex days @@ -1001,7 +1001,7 @@ Returns the year (as an integer 1582 or greater) corresponding to @var{date}. @end deftypefn -@node Time & Date Arithmetic +@node Time and Date Arithmetic @subsubsection Time and Date Arithmetic @cindex time, mathematical properties of @@ -1025,7 +1025,7 @@ accuracy of some procedures may be affected. If necessary, convert times or dates in seconds to some other unit, like days or years, before performing analysis. -PSPP supplies a few functions for date arithmetic: +@pspp{} supplies a few functions for date arithmetic: @deftypefn {Function} {} DATEDIFF (@var{date2}, @var{date1}, @var{unit}) Returns the span of time from @var{date1} to @var{date2} in terms of @@ -1077,7 +1077,8 @@ yields the value of that variable for the case @var{n} before the current one. Results in system-missing (for numeric variables) or blanks (for string variables) for the first @var{n} cases. -@code{LAG} obtains values from the cases that become the new active file +@code{LAG} obtains values from the cases that become the new active +dataset after a procedure executes. Thus, @code{LAG} will not return values from cases dropped by transformations such as @cmd{SELECT IF}, and transformations like @cmd{COMPUTE} that modify data will change the @@ -1097,7 +1098,7 @@ use of a large value will increase memory consumption. @cindex Julian date @deftypefn {Function} {} YRMODA (@var{year}, @var{month}, @var{day}) @var{year} is a year, either between 0 and 99 or at least 1582. -Unlike other PSPP date functions, years between 0 and 99 always +Unlike other @pspp{} date functions, years between 0 and 99 always correspond to 1900 through 1999. @var{month} is a month between 1 and 13. @var{day} is a day between 0 and 31. A @var{day} of 0 refers to the last day of the previous month, and a @var{month} of 13 refers to @@ -1120,7 +1121,7 @@ associated label, then this function returns the empty string. @node Statistical Distribution Functions @subsection Statistical Distribution Functions -PSPP can calculate several functions of standard statistical +@pspp{} can calculate several functions of standard statistical distributions. These functions are named systematically based on the function and the distribution. The table below describes the statistical distribution functions in general: @@ -1235,7 +1236,7 @@ Exponential distribution with scale parameter @var{a}. The inverse of Exponential power distribution with positive scale parameter @var{a} and nonnegative power parameter @var{b}. Constraints: @var{a} > 0, @var{b} >= 0, @var{x} >= 0, 0 <= @var{p} <= 1. This distribution is a -PSPP extension. +@pspp{} extension. @end deftypefn @deftypefn {Function} {} PDF.F (@var{x}, @var{df1}, @var{df2}) @@ -1340,7 +1341,7 @@ Equivalent to RV.NORMAL(0, @var{sigma}). @deftypefn {Function} {} PDF.NTAIL (@var{x}, @var{a}, @var{sigma}) @deftypefnx {Function} {} RV.NTAIL (@var{a}, @var{sigma}) Normal tail distribution with lower limit @var{a} and standard -deviation @var{sigma}. This distribution is a PSPP extension. +deviation @var{sigma}. This distribution is a @pspp{} extension. Constraints: @var{a} > 0, @var{x} > @var{a}, 0 < @var{p} < 1. @end deftypefn @@ -1358,14 +1359,14 @@ parameter @var{b}. Constraints: @var{a} > 0, @var{b} > 0, @var{x} >= @deftypefnx {Function} {} IDF.RAYLEIGH (@var{p}, @var{sigma}) @deftypefnx {Function} {} RV.RAYLEIGH (@var{sigma}) Rayleigh distribution with scale parameter @var{sigma}. This -distribution is a PSPP extension. Constraints: @var{sigma} > 0, +distribution is a @pspp{} extension. Constraints: @var{sigma} > 0, @var{x} > 0. @end deftypefn @deftypefn {Function} {} PDF.RTAIL (@var{x}, @var{a}, @var{sigma}) @deftypefnx {Function} {} RV.RTAIL (@var{a}, @var{sigma}) Rayleigh tail distribution with lower limit @var{a} and scale -parameter @var{sigma}. This distribution is a PSPP extension. +parameter @var{sigma}. This distribution is a @pspp{} extension. Constraints: @var{a} > 0, @var{sigma} > 0, @var{x} > @var{a}. @end deftypefn @@ -1398,14 +1399,14 @@ distribution takes an additional parameter @var{lambda}. Constraints: @deftypefnx {Function} {} CDF.T1G (@var{x}, @var{a}, @var{b}) @deftypefnx {Function} {} IDF.T1G (@var{p}, @var{a}, @var{b}) Type-1 Gumbel distribution with parameters @var{a} and @var{b}. This -distribution is a PSPP extension. Constraints: 0 < @var{p} < 1. +distribution is a @pspp{} extension. Constraints: 0 < @var{p} < 1. @end deftypefn @deftypefn {Function} {} PDF.T2G (@var{x}, @var{a}, @var{b}) @deftypefnx {Function} {} CDF.T2G (@var{x}, @var{a}, @var{b}) @deftypefnx {Function} {} IDF.T2G (@var{p}, @var{a}, @var{b}) Type-2 Gumbel distribution with parameters @var{a} and @var{b}. This -distribution is a PSPP extension. Constraints: @var{x} > 0, 0 < +distribution is a @pspp{} extension. Constraints: @var{x} > 0, 0 < @var{p} < 1. @end deftypefn @@ -1475,7 +1476,7 @@ Constraints: 0 <= @var{p} < 1, @var{x} >= 1. @deftypefn {Function} {} PDF.NEGBIN (@var{x}, @var{n}, @var{p}) @deftypefnx {Function} {} CDF.NEGBIN (@var{x}, @var{n}, @var{p}) @deftypefnx {Function} {} RV.NEGBIN (@var{n}, @var{p}) -Negative binomial distribution with number of successes paramter +Negative binomial distribution with number of successes parameter @var{n} and probability of success parameter @var{p}. Constraints: integer @var{n} >= 0, 0 < @var{p} <= 1, integer @var{x} >= 1. @end deftypefn