Exponentiation with infix operators in (or operating on) the base
(Many programming languages, especially those with extended─precision integer arithmetic, usually
support one of **, ^, ↑ or some such for exponentiation.)
Some languages treat/honor infix operators when performing exponentiation (raising
numbers to some power by the language's exponentiation operator, if the computer
programming language has one).
Other programming languages may make use of the POW or some other BIF
(Built─In Ffunction), or some other library service.
If your language's exponentiation operator is not one of the usual ones, please comment on how to recognize it.
This task will deal with the case where there is some form of an infix operator operating
in (or operating on) the base.
- Example
A negative five raised to the 3rd power could be specified as:
-5 ** 3 or as -(5) ** 3 or as (-5) ** 3 or as something else
(Not all computer programming languages have an exponential operator and/or support these syntax expression(s).
- Task
-
- compute and display exponentiation with a possible infix operator, whether specified and/or implied/inferred.
- Raise the following numbers (integer or real):
- -5 and
- +5
- to the following powers:
- 2nd and
- 3rd
- using the following expressions (if applicable in your language):
- -x**p
- -(x)**p
- (-x)**p
- -(x**p)
- Show here (on this page) the four (or more) types of symbolic expressions for each number and power.
Try to present the results in the same format/manner as the other programming entries to make any differences apparent.
The variables may be of any type(s) that is/are applicable in your language.
- Related tasks
- exponentiation order
- exponentiation operator
- arbitrary precision integers (include)
- Parsing/RPN to infix conversion
- operator precedence
Factor
<lang factor>USING: infix locals prettyprint sequences sequences.generalizations sequences.repeating ;
- row ( x p -- seq )
x p "-x**p" [infix -x**p infix] "-(x)**p" [infix -(x)**p infix] "(-x)**p" [infix (-x)**p infix] "-(x**p)" [infix -(x**p) infix] 10 narray ;
{ "x value" "p value" } { "expression" "result" } 8 cycle append -5 2 row -5 3 row 5 2 row 5 3 row 5 narray simple-table.</lang>
- Output:
x value p value expression result expression result expression result expression result -5 2 -x**p 25 -(x)**p 25 (-x)**p 25 -(x**p) -25 -5 3 -x**p 125 -(x)**p 125 (-x)**p 125 -(x**p) 125 5 2 -x**p 25 -(x)**p 25 (-x)**p 25 -(x**p) -25 5 3 -x**p -125 -(x)**p -125 (-x)**p -125 -(x**p) -125
Raku
In Raku by default, infix exponentiation binds tighter than unary negation. It is trivial however to define your own infix operators with whatever precedence level meets the needs of your program.
A slight departure from the task specs. Use 1 + {expression} rather than just {expression} to better demonstrate the relative precedence levels. Where {expression} is one of:
-x{exponential operator}p-(x){exponential operator}p((-x){exponential operator}p)-(x{exponential operator}p)
Also add a different grouping: (1 + -x){exponential operator}p
<lang perl6>sub infix:<↑> is looser(&prefix:<->) { $^a ** $^b } sub infix:<^> is looser(&infix:<->) { $^a ** $^b }
use MONKEY;
for 'Default precedence: infix exponentiation is tighter (higher) precedence than unary negation.',
('1 + -$x**$p', '1 + (-$x)**$p', '1 + (-($x)**$p)', '(1 + -$x)**$p', '1 + -($x**$p)'),
"\nEasily modified: custom loose infix exponentiation is looser (lower) precedence than unary negation.",
('1 + -$x↑$p ', '1 + (-$x)↑$p ', '1 + (-($x)↑$p) ', '(1 + -$x)↑$p ', '1 + -($x↑$p) '),
"\nEven moreso: custom looser infix exponentiation is looser (lower) precedence than infix subtraction.",
('1 + -$x^$p ', '1 + (-$x)^$p ', '1 + (-($x)^$p) ', '(1 + -$x)^$p ', '1 + -($x^$p) ')
-> $message, $ops {
say $message;
for -5, 2, -5, 3, 5, 2, 5, 3 -> $x, $p {
printf "x = %2d p = %d", $x, $p;
-> $op { printf " │ %s = %4d", $op, EVAL $op } for |$ops;
print "\n";
}
}</lang>
- Output:
Default precedence: infix exponentiation is tighter (higher) precedence than unary negation. x = -5 p = 2 │ 1 + -$x**$p = -24 │ 1 + (-$x)**$p = 26 │ 1 + (-($x)**$p) = -24 │ (1 + -$x)**$p = 36 │ 1 + -($x**$p) = -24 x = -5 p = 3 │ 1 + -$x**$p = 126 │ 1 + (-$x)**$p = 126 │ 1 + (-($x)**$p) = 126 │ (1 + -$x)**$p = 216 │ 1 + -($x**$p) = 126 x = 5 p = 2 │ 1 + -$x**$p = -24 │ 1 + (-$x)**$p = 26 │ 1 + (-($x)**$p) = -24 │ (1 + -$x)**$p = 16 │ 1 + -($x**$p) = -24 x = 5 p = 3 │ 1 + -$x**$p = -124 │ 1 + (-$x)**$p = -124 │ 1 + (-($x)**$p) = -124 │ (1 + -$x)**$p = -64 │ 1 + -($x**$p) = -124 Easily modified: custom loose infix exponentiation is looser (lower) precedence than unary negation. x = -5 p = 2 │ 1 + -$x↑$p = 26 │ 1 + (-$x)↑$p = 26 │ 1 + (-($x)↑$p) = 26 │ (1 + -$x)↑$p = 36 │ 1 + -($x↑$p) = -24 x = -5 p = 3 │ 1 + -$x↑$p = 126 │ 1 + (-$x)↑$p = 126 │ 1 + (-($x)↑$p) = 126 │ (1 + -$x)↑$p = 216 │ 1 + -($x↑$p) = 126 x = 5 p = 2 │ 1 + -$x↑$p = 26 │ 1 + (-$x)↑$p = 26 │ 1 + (-($x)↑$p) = 26 │ (1 + -$x)↑$p = 16 │ 1 + -($x↑$p) = -24 x = 5 p = 3 │ 1 + -$x↑$p = -124 │ 1 + (-$x)↑$p = -124 │ 1 + (-($x)↑$p) = -124 │ (1 + -$x)↑$p = -64 │ 1 + -($x↑$p) = -124 Even moreso: custom looser infix exponentiation is looser (lower) precedence than infix subtraction. x = -5 p = 2 │ 1 + -$x^$p = 36 │ 1 + (-$x)^$p = 36 │ 1 + (-($x)^$p) = 26 │ (1 + -$x)^$p = 36 │ 1 + -($x^$p) = -24 x = -5 p = 3 │ 1 + -$x^$p = 216 │ 1 + (-$x)^$p = 216 │ 1 + (-($x)^$p) = 126 │ (1 + -$x)^$p = 216 │ 1 + -($x^$p) = 126 x = 5 p = 2 │ 1 + -$x^$p = 16 │ 1 + (-$x)^$p = 16 │ 1 + (-($x)^$p) = 26 │ (1 + -$x)^$p = 16 │ 1 + -($x^$p) = -24 x = 5 p = 3 │ 1 + -$x^$p = -64 │ 1 + (-$x)^$p = -64 │ 1 + (-($x)^$p) = -124 │ (1 + -$x)^$p = -64 │ 1 + -($x^$p) = -124
REXX
<lang rexx>/*REXX program shows exponentition with an infix operator (implied and/or specified).*/ _= '─'; ! = '║'; mJunct= '─╫─'; bJunct= '─╨─' /*define some special glyphs. */
say @(' x ', 5) @(" p ", 5) ! say @('value', 5) @("value", 5) copies(! @('expression',10) @("result",6)" ", 4) say @( , 5, _) @("", 5, _)copies(mJunct || @(, 10, _) @("", 6, _) , 4)
do x=-5 to 5 by 10 /*assign -5 and 5 to X. */
do p= 2 to 3 /*assign 2 and 3 to P. */
a = -x**p ; b = -(x)**p ; c = (-x)**p ; d = -(x**p)
ae= '-x**p'; be= "-(x)**p"; ce= '(-x)**p'; de= "-(x**p)"
say @(x,5) @(p,5) ! @(ae, 10) right(a, 5)" " ,
! @(be, 10) right(b, 5)" " ,
! @(ce, 10) right(c, 5)" " ,
! @(de, 10) right(d, 5)
end /*p*/
end /*x*/
say @( , 5, _) @(, 5, _)copies(bJunct || @(, 10, _) @(, 6, _) , 4) exit 0 /*stick a fork in it, we're all done. */ /*──────────────────────────────────────────────────────────────────────────────────────*/ @: parse arg txt, w, fill; if fill== then fill= ' '; return center( txt, w, fill) </lang>
- output when using the internal default input:
x p ║ value value ║ expression result ║ expression result ║ expression result ║ expression result ───── ──────╫─────────── ───────╫─────────── ───────╫─────────── ───────╫─────────── ────── -5 2 ║ -x**p 25 ║ -(x)**p 25 ║ (-x)**p 25 ║ -(x**p) -25 -5 3 ║ -x**p 125 ║ -(x)**p 125 ║ (-x)**p 125 ║ -(x**p) 125 5 2 ║ -x**p 25 ║ -(x)**p 25 ║ (-x)**p 25 ║ -(x**p) -25 5 3 ║ -x**p -125 ║ -(x)**p -125 ║ (-x)**p -125 ║ -(x**p) -125 ───── ──────╨─────────── ───────╨─────────── ───────╨─────────── ───────╨─────────── ──────
Wren
Wren uses the pow() method for exponentiation of numbers and, whilst it supports operator overloading, there is no way of adding a suitable infix operator to the existing Num class.
Also inheriting from the Num class is not recommended and will probably be banned altogether from the next version.
However, what we can do is to wrap Num objects in a new Num2 class and then add exponentiation and unary minus operators to that.
Ideally what we'd like to do is to use a new operator such as '**' for exponentiation (because '^' is the bitwise exclusive or operator) but we can only overload existing operators with their existing precedence and so, for the purposes of this task, '^' is the only realistic choice. <lang ecmascript>import "/fmt" for Fmt
class Num2 {
construct new(n) { _n = n }
n { _n}
^(exp) {
if (exp is Num2) exp = exp.n
return Num2.new(_n.pow(exp))
}
- { Num2.new(-_n) }
toString { _n.toString }
}
var ops = ["-x^p", "-(x)^p", "(-x)^p", "-(x^p)"] for (x in [Num2.new(-5), Num2.new(5)]) {
for (p in [Num2.new(2), Num2.new(3)]) {
Fmt.write("x = $2s p = $s | ", x, p)
Fmt.write("$s = $4s | ", ops[0], -x^p)
Fmt.write("$s = $4s | ", ops[1], -(x)^p)
Fmt.write("$s = $4s | ", ops[2], (-x)^p)
Fmt.print("$s = $4s", ops[3], -(x^p))
}
}</lang>
- Output:
x = -5 p = 2 | -x^p = 25 | -(x)^p = 25 | (-x)^p = 25 | -(x^p) = -25 x = -5 p = 3 | -x^p = 125 | -(x)^p = 125 | (-x)^p = 125 | -(x^p) = 125 x = 5 p = 2 | -x^p = 25 | -(x)^p = 25 | (-x)^p = 25 | -(x^p) = -25 x = 5 p = 3 | -x^p = -125 | -(x)^p = -125 | (-x)^p = -125 | -(x^p) = -125