WikEmacs - User contributions [en]

Calc

2016-02-22T01:57:17Z

Procyon ember:

Calc comes with [[GNU Emacs]] starting with version 22.

[http://www.gnu.org/software/emacs/manual/html_mono/calc.html The GNU Emacs Calculator]

[http://www.emacswiki.org/emacs/CategoryCalculators Category Calculators -Emacs Wiki-]

== from emacs lisp via calc-eval ==

Calc may be invoked from [[Emacs_Lisp]] via [https://www.gnu.org/software/emacs/manual/html_node/calc/Calling-Calc-from-Your-Programs.html#Calling-Calc-from-Your-Programs calc-eval]. Try these examples in a ''*scratch*'' or [[IELM]] buffer, or via a shell one-liner in [https://www.gnu.org/software/emacs/manual/html_node/emacs/Initial-Options.html#Initial-Options batch mode].

=== using calc-eval ===

''calc-eval'' accepts a string containing an [https://www.gnu.org/software/emacs/manual/html_node/calc/Algebraic-Entry.html#Algebraic-Entry algebraic expression] as its first argument, and returns the result of evaluating the expression in a string.

<source lang=lisp>
;; emacs lisp
(calc-eval "sqrt(2 ^ 16)"))
;; ==> "256"
</source>

<source lang=bash>
# shell
emacs -Q -batch --eval='(message "%s" (calc-eval "sqrt(2 ^ 16)"))'
# ==> 256
</source>

=== floating point numbers ===

[https://www.gnu.org/software/emacs/manual/html_node/calc/Floats.html#Floats Floats] default to 12 digits of [https://www.gnu.org/software/emacs/manual/html_node/calc/Precision.html#Precision precision], with the final digit rounded.

<source lang=lisp>
;; emacs lisp
(calc-eval (calc-eval "2 / 3")
;; ==> "0.666666666667"
</source>

<source lang=bash>
# shell
emacs -Q -batch --eval='(message "%s" (calc-eval "2 / 3"))'
# ==> 0.666666666667
</source>

'''Note:''' The shell examples use ''message'' to cause the evaluation result to be printed. In emacs lisp, printing is a [https://en.wikipedia.org/wiki/Side_effect_%28computer_science%29 side effect] which only occurs when you ask for it. ''IELM'' displays the result as a convenience, and ''*scratch*'' only inserts then result depending on how you invoke it (such as with [https://www.gnu.org/software/emacs/manual/html_node/emacs/Lisp-Interaction.html#Lisp-Interaction eval-print-last-sexp]). ''message'' doesn't preserve quotation marks around strings because its output is intended for humans, not the lisp reader. In ''-batch'' mode, ''message'' prints to standard error, but ''print'' could be used to direct results to standard output.

=== lists ===

If the string is a comma-delimited list of expressions, then a comma-delimited list of results will be returned.

<source lang=lisp>
;; emacs lisp
(calc-eval "9 / 5, trunc(9 / 5), 9 % 5")
;; ==> "1.8, 1, 4"
</source>

<source lang=bash>
# shell
emacs -Q -batch --eval='(message "%s" (calc-eval "9 / 5, trunc(9 / 5), 9 % 5"))'
# ==> 1.8, 1, 4
</source>

=== random numbers ===

[https://www.gnu.org/software/emacs/manual/html_node/calc/Random-Numbers.html#Random-Numbers Calc's random number generator] is seeded from the system time when calc is started. ''random(N)'' returns a non-negative integer less than ''N''. Your results should vary from the examples below.

<source lang=lisp>
;; emacs lisp
(calc-eval "1 + random(6), 1 + random(6), 1 + random(6)")
;; ==> "1, 4, 3"
</source>

<source lang=bash>
# shell
emacs -Q -batch --eval='(message "%s" (calc-eval "1 + random(6), 1 + random(6)"))'
# ==> 5, 2
</source>

=== fractions ===

[https://www.gnu.org/software/emacs/manual/html_node/calc/Fractions.html#Fractions Fractions] are written as ''NUMERATOR:DENOMINATOR'' to distinguish them from divison operations. Mixed fractions may be entered as ''WHOLE:NUMERATOR:DENOMINATOR''. Fraction results are reduced to lowest terms, and may be improper fractions.

<source lang=lisp>
;; emacs lisp
(calc-eval "2:1:4 + 1:2")
;; ==> "11:4"
</source>

<source lang=bash>
# shell
emacs -Q -batch --eval='(message "%s" (calc-eval "2:1:4 + 1:2"))'
# ==> 11:4
</source>

=== entering non-decimal integers ===

[https://www.gnu.org/software/emacs/manual/html_node/calc/Integers.html#Integers integers] may be entered as ''RADIX#VALUE'', where ''RADIX'' may range from 2 to 36 inclusive.

'''Caution!''' This is '''not''' the same [https://www.gnu.org/software/emacs/manual/html_node/elisp/Integer-Basics.html#Integer-Basics notation used by emacs lisp].

<source lang=lisp>
;; emacs lisp
(calc-eval "2#10 * 8#10")
;; ==> "16"
</source>

<source lang=bash>
# shell
emacs -Q -batch --eval='(message "%s" (calc-eval "2#10 * 8#10"))'
# ==> 16
</source>

== advanced calc-eval ==

If the first argument to ''calc-eval'' is a list, then the first element of the list should be an algebraic expression in a string. Remaining elements of the list are zero or more ''NAME VALUE'' pairs which specify [https://www.gnu.org/software/emacs/manual/html_node/calc/Mode-Settings.html#Mode-Settings mode settings].

'''Important:''' In emacs lisp <nowiki>'(foo)</nowiki> is a [https://www.gnu.org/software/emacs/manual/html_node/elisp/Quoting.html#Quoting quoted] list, but <nowiki>'</nowiki> (apostrophe) is special to the shell. Lisp expressions in previous shell examples were wrapped in <nowiki>'</nowiki> (apostrophe) symbols to prevent the shell from interpreting them. In the following shell examples, ''(quote (foo bar))'' makes a quoted list without breaking the [https://www.gnu.org/software/bash/manual/html_node/Quoting.html#Quoting shell quoting].

=== non-decimal integer results ===

<source lang=lisp>
;; emacs lisp
(calc-eval '("2 * 8" calc-number-radix 16))
;; ==> "16#10"
</source>

<source lang=bash>
# shell
emacs -Q -batch --eval='(message "%s" (calc-eval (quote ("20" calc-number-radix 16))))'
# ==> 16#14
</source>

=== setting numeric precision ===

<source lang=lisp>
;; emacs lisp
(calc-eval '("2 / 3" calc-internal-prec 20))
;; ==> "0.66666666666666666667"
</source>

<source lang=bash>
# shell
emacs -Q -batch --eval='(message "%s" (calc-eval (quote ("2 / 3" calc-internal-prec 20))))'
# ==> 0.66666666666666666667
</source>

=== setting angular mode ===

<source lang=lisp>
;; emacs lisp
(calc-eval '("arctan2(0, -1)" calc-internal-prec 20 calc-angle-mode rad))
;; ==> "3.1415926535897932385"
</source>

<source lang=bash>
# shell
emacs -Q -batch --eval='(message "%s" (calc-eval (quote ("arctan2(0, -1)" calc-angle-mode rad))))'
# ==> 3.14159265359
</source>

Regexp Search

2016-02-22T01:05:51Z

Procyon ember:

# {{CommandKeys|C-M-s|isearch-forward-regexp}} : incremental forward search matching regexp
# {{CommandKeys|C-M-r|isearch-backward-regexp}} : incremental backward search matching regexp

=== alternative ===

# invoke incremental search by either '''C-s''' (isearch-forward) or '''C-r''' (isearch-backward)
# note the ''I-search:'' prompt in the echo area
# type '''M-r'''
# note the ''Pending regexp I-search:'' prompt in the echo area

[[Category:Search]]

Calc

2016-02-21T19:54:48Z

Procyon ember:

Calc comes with [[GNU Emacs]] starting with version 22.

[http://www.gnu.org/software/emacs/manual/html_mono/calc.html The GNU Emacs Calculator]

[http://www.emacswiki.org/emacs/CategoryCalculators Category Calculators -Emacs Wiki-]

== from emacs lisp via calc-eval ==

Calc may be invoked from [[Emacs_Lisp]] via [https://www.gnu.org/software/emacs/manual/html_node/calc/Calling-Calc-from-Your-Programs.html#Calling-Calc-from-Your-Programs calc-eval]. Try these examples in a ''*scratch*'' or [[IELM]] buffer, or via a shell one-liner in [https://www.gnu.org/software/emacs/manual/html_node/emacs/Initial-Options.html#Initial-Options batch mode].

=== using calc-eval ===

''calc-eval'' accepts a string containing an [https://www.gnu.org/software/emacs/manual/html_node/calc/Algebraic-Entry.html#Algebraic-Entry algebraic expression] as its first argument, and returns the result of evaluating the expression in a string.

<source lang=lisp>
;; emacs lisp
(calc-eval "sqrt(2 ^ 16)"))
;; ==> "256"
</source>

<source lang=bash>
# shell
emacs -Q -batch --eval='(message "%s" (calc-eval "sqrt(2 ^ 16)"))'
# ==> 256
</source>

=== floating point numbers ===

[https://www.gnu.org/software/emacs/manual/html_node/calc/Floats.html#Floats Floats] default to 12 digits of [https://www.gnu.org/software/emacs/manual/html_node/calc/Precision.html#Precision precision], with the final digit rounded.

<source lang=lisp>
;; emacs lisp
(calc-eval (calc-eval "2 / 3")
;; ==> "0.666666666667"
</source>

<source lang=bash>
# shell
emacs -Q -batch --eval='(message "%s" (calc-eval "2 / 3"))'
# ==> 0.666666666667
</source>

'''Note:''' The shell example uses ''message'' to cause the result to be printed. In ''-batch'' mode, ''message'' prints to standard output. In emacs lisp, printing is a [https://en.wikipedia.org/wiki/Side_effect_%28computer_science%29 side effect] which only occurs when you ask for it. ''IELM'' displays evaluation results as a convenience, and ''*scratch*'' only inserts evaluation results depending on how you invoke it (such as with [https://www.gnu.org/software/emacs/manual/html_node/emacs/Lisp-Interaction.html#Lisp-Interaction eval-print-last-sexp]). ''message'' doesn't preserve quotation marks around strings because its output is intended for humans, not the lisp reader.

=== lists ===

If the string is a comma-delimited list of expressions, then a comma-delimited list of results will be returned.

<source lang=lisp>
;; emacs lisp
(calc-eval "9 / 5, trunc(9 / 5), 9 % 5")
;; ==> "1.8, 1, 4"
</source>

<source lang=bash>
# shell
emacs -Q -batch --eval='(message "%s" (calc-eval "9 / 5, trunc(9 / 5), 9 % 5"))'
# ==> 1.8, 1, 4
</source>

=== random numbers ===

[https://www.gnu.org/software/emacs/manual/html_node/calc/Random-Numbers.html#Random-Numbers Calc's random number generator] is seeded from the system time when calc is started. ''random(N)'' returns a non-negative integer less than ''N''. Your results should vary from the examples below.

<source lang=lisp>
;; emacs lisp
(calc-eval "1 + random(6), 1 + random(6), 1 + random(6)")
;; ==> "1, 4, 3"
</source>

<source lang=bash>
# shell
emacs -Q -batch --eval='(message "%s" (calc-eval "1 + random(6), 1 + random(6)"))'
# ==> 5, 2
</source>

=== fractions ===

[https://www.gnu.org/software/emacs/manual/html_node/calc/Fractions.html#Fractions Fractions] are written as ''NUMERATOR:DENOMINATOR'' to distinguish them from divison operations. Mixed fractions may be entered as ''WHOLE:NUMERATOR:DENOMINATOR''. Fraction results are reduced to lowest terms, and may be improper fractions.

<source lang=lisp>
;; emacs lisp
(calc-eval "2:1:4 + 1:2")
;; ==> "11:4"
</source>

<source lang=bash>
# shell
emacs -Q -batch --eval='(message "%s" (calc-eval "2:1:4 + 1:2"))'
# ==> 11:4
</source>

=== entering non-decimal integers ===

[https://www.gnu.org/software/emacs/manual/html_node/calc/Integers.html#Integers integers] may be entered as ''RADIX#VALUE'', where ''RADIX'' may range from 2 to 36 inclusive.

'''Caution!''' This is '''not''' the same [https://www.gnu.org/software/emacs/manual/html_node/elisp/Integer-Basics.html#Integer-Basics notation used by emacs lisp].

<source lang=lisp>
;; emacs lisp
(calc-eval "2#10 * 8#10")
;; ==> "16"
</source>

<source lang=bash>
# shell
emacs -Q -batch --eval='(message "%s" (calc-eval "2#10 * 8#10"))'
# ==> 16
</source>

== advanced calc-eval ==

If the first argument to ''calc-eval'' is a list, then the first element of the list should be an algebraic expression in a string. Remaining elements of the list are zero or more ''NAME VALUE'' pairs which specify [https://www.gnu.org/software/emacs/manual/html_node/calc/Mode-Settings.html#Mode-Settings mode settings].

'''Important:''' In emacs lisp <nowiki>'(foo)</nowiki> is a [https://www.gnu.org/software/emacs/manual/html_node/elisp/Quoting.html#Quoting quoted] list, but <nowiki>'</nowiki> (apostrophe) is special to the shell. Lisp expressions in previous shell examples were wrapped in <nowiki>'</nowiki> (apostrophe) symbols to prevent the shell from interpreting them. In the following shell examples, ''(quote (foo bar))'' makes a quoted list without breaking the [https://www.gnu.org/software/bash/manual/html_node/Quoting.html#Quoting shell quoting].

=== non-decimal integer results ===

<source lang=lisp>
;; emacs lisp
(calc-eval '("2 * 8" calc-number-radix 16))
;; ==> "16#10"
</source>

<source lang=bash>
# shell
emacs -Q -batch --eval='(message "%s" (calc-eval (quote ("20" calc-number-radix 16))))'
# ==> 16#14
</source>

=== setting numeric precision ===

<source lang=lisp>
;; emacs lisp
(calc-eval '("2 / 3" calc-internal-prec 20))
;; ==> "0.66666666666666666667"
</source>

<source lang=bash>
# shell
emacs -Q -batch --eval='(message "%s" (calc-eval (quote ("2 / 3" calc-internal-prec 20))))'
# ==> 0.66666666666666666667
</source>

=== setting angular mode ===

<source lang=lisp>
;; emacs lisp
(calc-eval '("arctan2(0, -1)" calc-internal-prec 20 calc-angle-mode rad))
;; ==> "3.1415926535897932385"
</source>

<source lang=bash>
# shell
emacs -Q -batch --eval='(message "%s" (calc-eval (quote ("arctan2(0, -1)" calc-angle-mode rad))))'
# ==> 3.14159265359
</source>