GNU Emacs @value{EMACSVER}.
@end ifnotinfo
-Copyright @copyright{} 1990-1991, 2001-2012 Free Software Foundation, Inc.
+Copyright @copyright{} 1990--1991, 2001--2014 Free Software Foundation, Inc.
@quotation
Permission is granted to copy, distribute and/or modify this document
entitled ``GNU Free Documentation License.''
(a) The FSF's Back-Cover Text is: ``You have the freedom to copy and
-modify this GNU manual. Buying copies from the FSF supports it in
-developing GNU and promoting software freedom.''
+modify this GNU manual.''
@end quotation
@end copying
this manual ought to be readable even if you don't know or use Emacs
regularly.
-This manual is divided into three major parts:@: the ``Getting
+This manual is divided into three major parts: the ``Getting
Started'' chapter you are reading now, the Calc tutorial, and the Calc
reference manual.
@c [when-split]
fair to give the user direct access to it, which in turn made it
practical to support fractions as well as floats. All these features
inspired me to look around for other data types that might be worth
-having.
+having.
Around this time, my friend Rick Koshi showed me his nifty new HP-28
calculator. It allowed the user to manipulate formulas as well as
Friday the 13th? @xref{Types Answer 5, 5}. (@bullet{})
(@bullet{}) @strong{Exercise 6.} How many leap years will there be
-between now and the year 10001 A.D.? @xref{Types Answer 6, 6}. (@bullet{})
+between now and the year 10001 AD@? @xref{Types Answer 6, 6}. (@bullet{})
@cindex Slope and angle of a line
@cindex Angle and slope of a line
rearranged. (This one is rather tricky; the solution at the end of
this chapter uses 6 rewrite rules. Hint: The @samp{constant(x)}
condition tests whether @samp{x} is a number.) @xref{Rewrites Answer
-6, 6}. (@bullet{})
+6, 6}. (@bullet{})
Just for kicks, try adding the rule @code{2+3 := 6} to @code{EvalRules}.
What happens? (Be sure to remove this rule afterward, or you might get
@smallexample
@group
___
-1: V 2
+1: V 2
.
a r a*(b+c) := a*b + a*c
apply to any product-of-sum it encounters---this rule may surprise
you if you put it into @code{EvalRules}!
-In the second rule, the sum of two O's is changed to the smaller O.
+In the second rule, the sum of two O's is changed to the smaller O@.
The optional constant coefficients are there mostly so that
@samp{O(x^2) - O(x^3)} and @samp{O(x^3) - O(x^2)} are handled
as well as @samp{O(x^2) + O(x^3)}.
@kindex h n
The @kbd{h n} or @kbd{h C-n} (@code{calc-view-news}) command displays
-the ``news'' or change history of Calc. This is kept in the file
-@file{README}, which Calc looks for in the same directory as the Calc
-source files.
+the ``news'' or change history of Emacs, and jumps to the most recent
+portion concerning Calc (if present). For older history, see the file
+@file{etc/CALC-NEWS} in the Emacs distribution.
@kindex h C-c
@kindex h C-d
numbers. HMS forms also for many purposes act as real numbers. These
types can be combined to form complex numbers, modulo forms, error forms,
or interval forms. (But these last four types cannot be combined
-arbitrarily:@: error forms may not contain modulo forms, for example.)
+arbitrarily: error forms may not contain modulo forms, for example.)
Finally, all these types of numbers may be combined into vectors,
matrices, or algebraic formulas.
notations for dates and times. @xref{Date Formats}.
Date forms are stored internally as numbers, specifically the number
-of days since midnight on the morning of December 31 of the year 1 BC.
+of days since midnight on the morning of December 31 of the year 1 BC@.
If the internal number is an integer, the form represents a date only;
if the internal number is a fraction or float, the form represents
a date and time. For example, @samp{<6:00am Thu Jan 10, 1991>}
of a date form. @xref{Packing and Unpacking}.
Date forms can go arbitrarily far into the future or past. Negative
-year numbers represent years BC. There is no ``year 0''; the day
+year numbers represent years BC@. There is no ``year 0''; the day
before @samp{<Mon Jan 1, +1>} is @samp{<Sun Dec 31, -1>}. These are
days 1 and 0 respectively in Calc's internal numbering scheme. The
Gregorian calendar is used for all dates, including dates before the
Gregorian calendar was invented (although that can be configured; see
below). Thus Calc's use of the day number @mathit{-10000} to
-represent August 15, 28 BC should be taken with a grain of salt.
+represent August 15, 28 BC should be taken with a grain of salt.
@cindex Julian calendar
@cindex Gregorian calendar
caused by the irregular Roman calendar that was used before that time.
The Julian calendar introduced an extra day in all years divisible by
four. After some initial confusion, the calendar was adopted around
-the year we call 8 AD. Some centuries later it became
+the year we call 8 AD@. Some centuries later it became
apparent that the Julian year of 365.25 days was itself not quite
right. In 1582 Pope Gregory XIII introduced the Gregorian calendar,
which added the new rule that years divisible by 100, but not by 400,
Gregorian calendar until 1918, and that year in Russia the day after
January 31 was February 14. Calc's reckoning therefore matches English
practice starting in 1752 and Russian practice starting in 1918, but
-disagrees with earlier dates in both countries.
+disagrees with earlier dates in both countries.
When the Julian calendar was introduced, it had January 1 as the first
day of the year. By the Middle Ages, many European countries
had changed the beginning of a new year to a different date, often to
a religious festival. Almost all countries reverted to using January 1
as the beginning of the year by the time they adopted the Gregorian
-calendar.
+calendar.
Some calendars attempt to mimic the historical situation by using the
Gregorian calendar for recent dates and the Julian calendar for older
dates. The @code{cal} program in most Unix implementations does this,
for example. While January 1 wasn't always the beginning of a calendar
year, these hybrid calendars still use January 1 as the beginning of
-the year even for older dates. The customizable variable
+the year even for older dates. The customizable variable
@code{calc-gregorian-switch} (@pxref{Customizing Calc}) can be set to
have Calc's date forms switch from the Julian to Gregorian calendar at
-any specified date.
+any specified date.
Today's timekeepers introduce an occasional ``leap second''.
These do not occur regularly and Calc does not take these minor
effects into account. (If it did, it would have to report a
-non-integer number of days between, say,
-@samp{<12:00am Mon Jan 1, 1900>} and
+non-integer number of days between, say,
+@samp{<12:00am Mon Jan 1, 1900>} and
@samp{<12:00am Sat Jan 1, 2000>}.)
@cindex Julian day counting
Another day counting system in common use is, confusingly, also called
-``Julian.'' The Julian day number is the numbers of days since
-12:00 noon (GMT) on Jan 1, 4713 BC, which in Calc's scheme (in GMT)
-is @mathit{-1721423.5} (recall that Calc starts at midnight instead
-of noon). Thus to convert a Calc date code obtained by unpacking a
-date form into a Julian day number, simply add 1721423.5 after
+``Julian.'' Julian days go from noon to noon. The Julian day number
+is the numbers of days since 12:00 noon (GMT) on November 24, 4714 BC
+in the Gregorian calendar (i.e., January 1, 4713 BC in the Julian
+calendar). In Calc's scheme (in GMT) the Julian day origin is
+@mathit{-1721422.5}, because Calc starts at midnight instead of noon.
+Thus to convert a Calc date code obtained by unpacking a
+date form into a Julian day number, simply add 1721422.5 after
compensating for the time zone difference. The built-in @kbd{t J}
command performs this conversion for you.
up by other astronomers. (At the time, noon was the start of the
astronomical day. Herschel originally suggested counting the days
since Jan 1, 4713 BC at noon Alexandria time; this was later amended to
-noon GMT.) Julian day numbering is largely used in astronomy.
+noon GMT@.) Julian day numbering is largely used in astronomy.
@cindex Unix time format
The Unix operating system measures time as an integer number of
leaving the first, third, fourth, and so on; @kbd{M-3 M-@key{DEL}} deletes
the third stack element.
+The above commands do not depend on the location of the cursor.
+If the customizable variable @code{calc-context-sensitive-enter} is
+non-@code{nil} (@pxref{Customizing Calc}), these commands will become
+context sensitive. For example, instead of duplicating the top of the stack,
+@key{RET} will copy the element at the cursor to the top of the
+stack. With a positive numeric prefix, a copy of the element at the
+cursor and the appropriate number of preceding elements will be placed
+at the top of the stack. A negative prefix will still duplicate the
+specified element of the stack regardless of the cursor position.
+Similarly, @key{DEL} will remove the corresponding elements from the
+stack.
+
@kindex @key{TAB}
@pindex calc-roll-down
To exchange the top two elements of the stack, press @key{TAB}
A common technique is to set the simplification mode down to the lowest
amount of simplification you will allow to be applied automatically, then
use manual commands like @kbd{a s} and @kbd{c c} (@code{calc-clean}) to
-perform higher types of simplifications on demand.
+perform higher types of simplifications on demand.
@node Declarations, Display Modes, Simplification Modes, Mode Settings
@section Declarations
function checks for nonnegative reals, i.e., reals greater than or
equal to zero. Note that Calc's algebraic simplifications, which are
effectively applied to all conditions in rewrite rules, can simplify
-an expression like @expr{x > 0} to 1 or 0 using @code{dpos}.
+an expression like @expr{x > 0} to 1 or 0 using @code{dpos}.
So the actual functions @code{dpos}, @code{dneg}, and @code{dnonneg}
are rarely necessary.
functions, your date formats should avoid using the @samp{#} character.
@menu
+* ISO 8601::
* Date Formatting Codes::
* Free-Form Dates::
* Standard Date Formats::
@end menu
-@node Date Formatting Codes, Free-Form Dates, Date Formats, Date Formats
+@node ISO 8601, Date Formatting Codes, Date Formats, Date Formats
+@subsubsection ISO 8601
+
+@noindent
+@cindex ISO 8601
+The same date can be written down in different formats and Calc tries
+to allow you to choose your preferred format. Some common formats are
+ambiguous, however; for example, 10/11/2012 means October 11,
+2012 in the United States but it means November 10, 2012 in
+Europe. To help avoid such ambiguities, the International Organization
+for Standardization (ISO) provides the ISO 8601 standard, which
+provides three different but easily distinguishable and unambiguous
+ways to represent a date.
+
+The ISO 8601 calendar date representation is
+
+@example
+ @var{YYYY}-@var{MM}-@var{DD}
+@end example
+
+@noindent
+where @var{YYYY} is the four digit year, @var{MM} is the two-digit month
+number (01 for January to 12 for December), and @var{DD} is the
+two-digit day of the month (01 to 31). (Note that @var{YYYY} does not
+correspond to Calc's date formatting code, which will be introduced
+later.) The year, which should be padded with zeros to ensure it has at
+least four digits, is the Gregorian year, except that the year before
+0001 (1 AD) is the year 0000 (1 BC). The date October 11, 2012 is
+written 2012-10-11 in this representation and November 10, 2012 is
+written 2012-11-10.
+
+The ISO 8601 ordinal date representation is
+
+@example
+ @var{YYYY}-@var{DDD}
+@end example
+
+@noindent
+where @var{YYYY} is the year, as above, and @var{DDD} is the day of the year.
+The date December 31, 2011 is written 2011-365 in this representation
+and January 1, 2012 is written 2012-001.
+
+The ISO 8601 week date representation is
+
+@example
+ @var{YYYY}-W@var{ww}-@var{D}
+@end example
+
+@noindent
+where @var{YYYY} is the ISO week-numbering year, @var{ww} is the two
+digit week number (preceded by a literal ``W''), and @var{D} is the day
+of the week (1 for Monday through 7 for Sunday). The ISO week-numbering
+year is based on the Gregorian year but can differ slightly. The first
+week of an ISO week-numbering year is the week with the Gregorian year's
+first Thursday in it (equivalently, the week containing January 4);
+any day of that week (Monday through Sunday) is part of the same ISO
+week-numbering year, any day from the previous week is part of the
+previous year. For example, January 4, 2013 is on a Friday, and so
+the first week for the ISO week-numbering year 2013 starts on
+Monday, December 31, 2012. The day December 31, 2012 is then part of the
+Gregorian year 2012 but ISO week-numbering year 2013. In the week
+date representation, this week goes from 2013-W01-1 (December 31,
+2012) to 2013-W01-7 (January 6, 2013).
+
+All three ISO 8601 representations arrange the numbers from most
+significant to least significant; as well as being unambiguous
+representations, they are easy to sort since chronological order in
+this formats corresponds to lexicographical order. The hyphens are
+sometimes omitted.
+
+The ISO 8601 standard uses a 24 hour clock; a particular time is
+represented by @var{hh}:@var{mm}:@var{ss} where @var{hh} is the
+two-digit hour (from 00 to 24), @var{mm} is the two-digit minute (from
+00 to 59) and @var{ss} is the two-digit second. The seconds or minutes
+and seconds can be omitted, and decimals can be added. If a date with a
+time is represented, they should be separated by a literal ``T'', so noon
+on December 13, 2012 can be represented as 2012-12-13T12:00.
+
+@node Date Formatting Codes, Free-Form Dates, ISO 8601, Date Formats
@subsubsection Date Formatting Codes
@noindent
match exactly; letter fields must correspond to suitable text in
the input. If this doesn't work, Calc checks if the input is a
simple number; if so, the number is interpreted as a number of days
-since Jan 1, 1 AD. Otherwise, Calc tries a much more relaxed and
+since Dec 31, 1 BC@. Otherwise, Calc tries a much more relaxed and
flexible algorithm which is described in the next section.
Weekday names are ignored during reading.
Year: ``1991'' for 1991, ``23'' for 23 AD.
@item YYYY
Year: ``1991'' for 1991, ``+23'' for 23 AD.
+@item ZYYY
+Year: ``1991'' for 1991, ``0023'' for 23 AD, ``0000'' for 1 BC.
+@item IYYY
+Year: ISO 8601 week-numbering year.
@item aa
Year: ``ad'' or blank.
@item AA
@item AAA
Year: ``AD '' or blank.
@item aaaa
-Year: ``a.d.'' or blank.
+Year: ``a.d.@:'' or blank.
@item AAAA
Year: ``A.D.'' or blank.
@item bb
@item BBB
Year: `` BC'' or blank.
@item bbbb
-Year: ``b.c.'' or blank.
+Year: ``b.c.@:'' or blank.
@item BBBB
Year: ``B.C.'' or blank.
@item M
Day: `` 7'' for 7th day of month.
@item W
Weekday: ``0'' for Sunday, ``6'' for Saturday.
+@item w
+Weekday: ``1'' for Monday, ``7'' for Sunday.
@item WWW
Weekday: ``SUN'' for Sunday.
@item Www
Weekday: ``SUNDAY'' for Sunday.
@item Wwww
Weekday: ``Sunday'' for Sunday.
+@item Iww
+Week number: ISO 8601 week number, ``W01'' for week 1.
@item d
Day of year: ``34'' for Feb. 3.
@item ddd
Day of year: ``034'' for Feb. 3.
@item bdd
Day of year: `` 34'' for Feb. 3.
+@item T
+Letter: Literal ``T''.
@item h
Hour: ``5'' for 5 AM; ``17'' for 5 PM.
@item hh
@item PP
AM/PM: ``AM'' or ``PM''.
@item pppp
-AM/PM: ``a.m.'' or ``p.m.''.
+AM/PM: ``a.m.@:'' or ``p.m.''.
@item PPPP
AM/PM: ``A.M.'' or ``P.M.''.
@item m
@samp{p.m.}, and @samp{mid} are also understood. Obviously
@samp{noon} and @samp{midnight} are allowed only on 12:00:00.
The words @samp{noon}, @samp{mid}, and @samp{midnight} are also
-recognized with no number attached.
+recognized with no number attached. Midnight will represent the
+beginning of a day.
If there is no AM/PM indicator, the time is interpreted in 24-hour
format.
-To read the date portion, all words and numbers are isolated
-from the string; other characters are ignored. All words must
-be either month names or day-of-week names (the latter of which
-are ignored). Names can be written in full or as three-letter
+When reading the date portion, Calc first checks to see if it is an
+ISO 8601 week-numbering date; if the string contains an integer
+representing the year, a ``W'' followed by two digits for the week
+number, and an integer from 1 to 7 representing the weekday (in that
+order), then all other characters are ignored and this information
+determines the date. Otherwise, all words and numbers are isolated
+from the string; other characters are ignored. All words must be
+either month names or day-of-week names (the latter of which are
+ignored). Names can be written in full or as three-letter
abbreviations.
Large numbers, or numbers with @samp{+} or @samp{-} signs,
@samp{j<, h:mm:ss>} (Julian day plus time)
@item 9
@samp{YYddd< hh:mm:ss>} (Year-day format)
+@item 10
+@samp{ZYYY-MM-DD Www< hh:mm>} (Org mode format)
+@item 11
+@samp{IYYY-Iww-w<Thh:mm:ss>} (ISO 8601 week numbering format)
@end table
@node Truncating the Stack, Justification, Date Formats, Display Modes
a different table of operators. Hexadecimal numbers are entered and
displayed with a preceding dollar sign. (Thus the regular meaning of
@kbd{$2} during algebraic entry does not work in Pascal mode, though
-@kbd{$} (and @kbd{$$}, etc.) not followed by digits works the same as
+@kbd{$} (and @kbd{$$}, etc.)@: not followed by digits works the same as
always.) No special provisions are made for other non-decimal numbers,
vectors, and so on, since there is no universally accepted standard way
of handling these in Pascal.
The @kbd{d W} (@code{calc-maple-language}) command selects the
conventions of Maple.
-Maple's language is much like C. Underscores are allowed in symbol
+Maple's language is much like C@. Underscores are allowed in symbol
names; square brackets are used for subscripts; explicit @samp{*}s for
multiplications are required. Use either @samp{^} or @samp{**} to
denote powers.
If the simplification mode is set below basic simplification, it is raised
for the purposes of this command. Thus, @kbd{c c} applies the basic
simplifications even if their automatic application is disabled.
-@xref{Simplification Modes}.
+@xref{Simplification Modes}.
@cindex Roundoff errors, correcting
A numeric prefix argument to @kbd{c c} sets the floating-point precision
@pindex calc-date
@tindex date
The @kbd{t D} (@code{calc-date}) [@code{date}] command converts a
-date form into a number, measured in days since Jan 1, 1 AD. The
+date form into a number, measured in days since Jan 1, 1 AD@. The
result will be an integer if @var{date} is a pure date form, or a
fraction or float if @var{date} is a date/time form. Or, if its
argument is a number, it converts this number into a date form.
@cindex Julian day counts, conversions
The @kbd{t J} (@code{calc-julian}) [@code{julian}] command converts
a date form into a Julian day count, which is the number of days
-since noon (GMT) on Jan 1, 4713 BC. A pure date is converted to an
+since noon (GMT) on Jan 1, 4713 BC@. A pure date is converted to an
integer Julian count representing noon of that day. A date/time form
is converted to an exact floating-point Julian count, adjusted to
interpret the date form in the current time zone but the Julian
exercise for the reader is to modify this formula to yield the same day
if the input is already a Wednesday. Another interesting exercise is
to preserve the time-of-day portion of the input (@code{newweek} resets
-the time to midnight; hint:@: how can @code{newweek} be defined in terms
+the time to midnight; hint: how can @code{newweek} be defined in terms
of the @code{weekday} function?).
@ignore
the user-level @code{pwday} function described in the previous
section. It takes four arguments: The floating-point date value,
the corresponding six-element date list, the day-of-month number,
-and the weekday number (0-6).
+and the weekday number (0--6).
The default daylight saving hook ignores the time zone name, but a
more sophisticated hook could use different algorithms for different
ten, however, the numbers should be completely unbiased.
The Gaussian random numbers generated by @samp{random(0.0)} use the
-``polar'' method described in Knuth section 3.4.1C. This method
+``polar'' method described in Knuth section 3.4.1C@. This method
generates a pair of Gaussian random numbers at a time, so only every
other call to @samp{random(0.0)} will require significant calculations.
If you give a numeric prefix argument of 2 to @kbd{a v}, it simplifies
using Calc's algebraic simplifications; @pxref{Simplifying Formulas}.
If you give a numeric prefix of 3 or more, it uses Extended
-Simplification mode (@kbd{a e}).
+Simplification mode (@kbd{a e}).
If you give a negative prefix argument @mathit{-1}, @mathit{-2}, or @mathit{-3},
it simplifies in the corresponding mode but only works on the top-level
are mapped, the direction of the second inequality is reversed to
match the first: Using @kbd{a M +} on @samp{a < b} and @samp{a > 2}
reverses the latter to get @samp{2 < a}, which then allows the
-combination @samp{a + 2 < b + a}, which the algebraic simplifications
+combination @samp{a + 2 < b + a}, which the algebraic simplifications
can reduce to @samp{2 < b}.
Using @kbd{a M *}, @kbd{a M /}, @kbd{a M n}, or @kbd{a M &} to negate
@kbd{Q} [@code{sqrt}], the arguments are simply popped from the stack
and collected into a suitable function call, which is then simplified
(the arguments being simplified first as part of the process, as
-described above).
+described above).
Even the basic set of simplifications are too numerous to describe
completely here, but this section will describe the ones that apply to the
mode. If you have switched to a different simplification mode, you can
switch back with the @kbd{m A} command. Even in other simplification
modes, the @kbd{a s} command will use these algebraic simplifications to
-simplify the formula.
+simplify the formula.
There is a variable, @code{AlgSimpRules}, in which you can put rewrites
to be applied. Its use is analogous to @code{EvalRules},
simplifications will not change @expr{x y + y x} to @expr{2 x y},
but the algebraic simplifications; it first rewrites the sum to
@expr{x y + x y} which can then be recognized as a sum of identical
-terms.
+terms.
The canonical ordering used to sort terms of products has the
property that real-valued numbers, interval forms and infinities
for example, @expr{(4 x + 6) / 8 x} simplifies to @expr{(2 x + 3) / 4 x}.
Non-constant common factors are not found even by algebraic
-simplifications. To cancel the factor @expr{a} in
+simplifications. To cancel the factor @expr{a} in
@expr{(a x + a) / a^2} you could first use @kbd{j M} on the product
@expr{a x} to Merge the numerator to @expr{a (1+x)}, which can then be
-simplified successfully.
+simplified successfully.
@tex
\bigskip
@tindex esimplify
Calc is capable of performing some simplifications which may sometimes
be desired but which are not ``safe'' in all cases. The @kbd{a e}
-(@code{calc-simplify-extended}) [@code{esimplify}] command
+(@code{calc-simplify-extended}) [@code{esimplify}] command
applies the algebraic simplifications as well as these extended, or
``unsafe'', simplifications. Use this only if you know the values in
your formula lie in the restricted ranges for which these
@vindex IntegSimpRules
Another set of rules, stored in @code{IntegSimpRules}, are applied
every time the integrator uses algebraic simplifications to simplify an
-intermediate result. For example, putting the rule
+intermediate result. For example, putting the rule
@samp{twice(x) := 2 x} into @code{IntegSimpRules} would tell Calc to
convert the @code{twice} function into a form it knows whenever
-integration is attempted.
+integration is attempted.
One more way to influence the integrator is to define a function with
the @kbd{Z F} command (@pxref{Algebraic Definitions}). Calc's
been matched to something else the two values must be equal; if the
meta-variable is new then it is bound to the result of the expression.
This variable can then appear in later conditions, and on the righthand
-side of the rule.
+side of the rule.
In fact, @expr{v} may be any pattern in which case the result of
evaluating @expr{x} is matched to that pattern, binding any
meta-variables that appear in that pattern. Note that @code{let}
formula. The variable @code{AlgSimpRules} holds rules for this purpose.
The @kbd{a s} command will apply @code{EvalRules} and
@code{AlgSimpRules} to the formula, as well as all of its built-in
-simplifications.
+simplifications.
Most of the special limitations for @code{EvalRules} don't apply to
@code{AlgSimpRules}. Calc simply does an @kbd{a r AlgSimpRules}
simplifications. It then applies its own built-in simplifications
throughout the formula, and then repeats these two steps (along with
applying the default simplifications) until no further changes are
-possible.
+possible.
@cindex @code{ExtSimpRules} variable
@cindex @code{UnitSimpRules} variable
If the units you request are inconsistent with the original units, the
number will be converted into your units times whatever ``remainder''
-units are left over. For example, converting @samp{55 mph} into acres
+units are left over. (This can be disabled; @pxref{Customizing Calc}.)
+For example, converting @samp{55 mph} into acres
produces @samp{6.08e-3 acre / m s}. (Recall that multiplication binds
more strongly than division in Calc formulas, so the units here are
acres per meter-second.) Remainder units are expressed in terms of
``fundamental'' units like @samp{m} and @samp{s}, regardless of the
input units.
-If you want to disallow using inconsistent units, you can set the customizable variable
-@code{calc-ensure-consistent-units} to @code{t} (@pxref{Customizing Calc}). In this case,
-if you request units which are inconsistent with the original units, you will be warned about
-it and no conversion will occur.
-
One special exception is that if you specify a single unit name, and
a compatible unit appears somewhere in the units expression, then
that compatible unit will be converted to the new unit and the
If the value on the stack does not contain any units, @kbd{u c} will
prompt first for the old units which this value should be considered
-to have, then for the new units. Assuming the old and new units you
-give are consistent with each other, the result also will not contain
-any units. For example, @kbd{@w{u c} cm @key{RET} in @key{RET}}
-converts the number 2 on the stack to 5.08.
+to have, then for the new units. (If the value on the stack can be
+simplified so that it doesn't contain any units, like @samp{ft/in} can
+be simplified to 12, then @kbd{u c} will still prompt for both old
+units and new units. Assuming the old and new units you give are
+consistent with each other, the result also will not contain any
+units. For example, @kbd{@w{u c} cm @key{RET} in @key{RET}} converts
+the number 2 on the stack to 5.08.
@kindex u b
@pindex calc-base-units
All current modes apply when an @samp{=>} operator is computed,
including the current simplification mode. Recall that the
formula @samp{arcsin(sin(x))} will not be handled by Calc's algebraic
-simplifications, but Calc's unsafe simplifications will reduce it to
+simplifications, but Calc's unsafe simplifications will reduce it to
@samp{x}. If you enter @samp{arcsin(sin(x)) =>} normally, the result
-will be @samp{arcsin(sin(x)) => arcsin(sin(x))}. If you change to
+will be @samp{arcsin(sin(x)) => arcsin(sin(x))}. If you change to
Extended Simplification mode, the result will be
@samp{arcsin(sin(x)) => x}. However, just pressing @kbd{a e}
once will have no effect on @samp{arcsin(sin(x)) => arcsin(sin(x))},
@kindex g O
@pindex calc-graph-output
The @kbd{g O} (@code{calc-graph-output}) command sets the name of the
-output file used by GNUPLOT. For some devices, notably @code{x11} and
+output file used by GNUPLOT@. For some devices, notably @code{x11} and
@code{windows}, there is no output file and this information is not
used. Many other ``devices'' are really file formats like
@code{postscript}; in these cases the output in the desired format
effect if the current device is @code{windows}.
The buffer called @samp{*Gnuplot Trail*} holds a transcript of the
-session with GNUPLOT. This shows the commands Calc has ``typed'' to
+session with GNUPLOT@. This shows the commands Calc has ``typed'' to
GNUPLOT and the responses it has received. Calc tries to notice when an
error message has appeared here and display the buffer for you when
this happens. You can check this buffer yourself if you suspect
which is not a Lisp list.
Large integers are stored as lists of the form @samp{(bigpos @var{d0}
-@var{d1} @var{d2} @dots{})} for positive integers 1000000 or more, or
-@samp{(bigneg @var{d0} @var{d1} @var{d2} @dots{})} for negative integers
-@mathit{-1000000} or less. Each @var{d} is a base-1000 ``digit,'' a Lisp integer
-from 0 to 999. The least significant digit is @var{d0}; the last digit,
+@var{d1} @var{d2} @dots{})} for sufficiently large positive integers
+(where ``sufficiently large'' depends on the machine), or
+@samp{(bigneg @var{d0} @var{d1} @var{d2} @dots{})} for negative
+integers. Each @var{d} is a base-@expr{10^n} ``digit'' (where again,
+@expr{n} depends on the machine), a Lisp integer from 0 to
+99@dots{}9. The least significant digit is @var{d0}; the last digit,
@var{dn}, which is always nonzero, is the most significant digit. For
-example, the integer @mathit{-12345678} is stored as @samp{(bigneg 678 345 12)}.
+example, the integer @mathit{-12345678} might be stored as
+@samp{(bigneg 678 345 12)}.
The distinction between small and large integers is entirely hidden from
the user. In @code{defmath} definitions, the Lisp predicate @code{integerp}
Date forms are stored as @samp{(date @var{n})}, where @var{n} is
a real number that counts days since midnight on the morning of
-January 1, 1 AD. If @var{n} is an integer, this is a pure date
+January 1, 1 AD@. If @var{n} is an integer, this is a pure date
form. If @var{n} is a fraction or float, this is a date/time form.
Modulo forms are stored as @samp{(mod @var{n} @var{m})}, where @var{m} is a
function is used by the @kbd{V S} vector-sorting command, and also
by Calc's algebraic simplifications to put the terms of a product into
canonical order: This allows @samp{x y + y x} to be simplified easily to
-@samp{2 x y}.
+@samp{2 x y}.
@end defun
@defun equal x y
before the call to @code{normalize}) and, if it has changed,
the entire procedure is repeated (starting with @code{normalize})
until no further changes occur. Usually only two iterations are
-needed:@: one to simplify the formula, and another to verify that no
+needed: one to simplify the formula, and another to verify that no
further simplifications were possible.
@end defun
is @code{nil}.
@end defvar
+@defvar calc-context-sensitive-enter
+The commands @code{calc-enter} and @code{calc-pop} will typically
+duplicate the top of the stack. If
+@code{calc-context-sensitive-enter} is non-@code{nil}, then the
+@code{calc-enter} will copy the element at the cursor to the
+top of the stack and @code{calc-pop} will delete the element at the
+cursor. The default value of @code{calc-context-sensitive-enter} is
+@code{nil}.
+@end defvar
+
@defvar calc-undo-length
The variable @code{calc-undo-length} determines the number of undo
steps that Calc will keep track of when @code{calc-quit} is called.
@defvar calc-gregorian-switch
See @ref{Date Forms}.@*
-The variable @code{calc-gregorian-switch} is either a list of integers
+The variable @code{calc-gregorian-switch} is either a list of integers
@code{(@var{YEAR} @var{MONTH} @var{DAY})} or @code{nil}.
If it is @code{nil}, then Calc's date forms always represent Gregorian dates.
Otherwise, @code{calc-gregorian-switch} represents the date that the
-calendar switches from Julian dates to Gregorian dates;
+calendar switches from Julian dates to Gregorian dates;
@code{(@var{YEAR} @var{MONTH} @var{DAY})} will be the first Gregorian
date. The customization buffer will offer several standard dates to
choose from, or the user can enter their own date.
@c 17
@item
-A prefix argument specifies a day number (0-6, 0-31, or 0-366).
+A prefix argument specifies a day number (0--6, 0--31, or 0--366).
@c 18
@item
HCoop / bpt / emacs.git / blobdiff