Temperature conversion
There are quite a number of temperature scales. For this task we will concentrate on 4 of the perhaps best-known ones: Kelvin, Celcius, Fahrenheit and Rankine.
The Celcius and Kelvin scales have the same magnitude, but different null points.
0 degrees Celcius corresponds to 273.15 kelvin.
0 kelvin is absolute zero.
The Fahrenheit and Rankine scales also have the same magnitude, but different null points.
0 degrees Fahrenheit corresponds to 459.67 degrees Rankine.
0 degrees Rankine is absolute zero.
The Celcius/Kelvin and Fahrenheit/Rankine scales have a ratio of 5 : 9.
Write code that accepts a value of kelvin, converts it to values on the three other scales and prints the result. For instance:
K 21.00 C -252.15 F -421.87 R 37.80
D
<lang d>double kelvinToCelsius(in double k) pure nothrow @safe {
return k - 273.15;
}
double kelvinToFahrenheit(in double k) pure nothrow @safe {
return k * 1.8 - 459.67;
}
double kelvinToRankine(in double k) pure nothrow @safe {
return k * 1.8;
}
unittest {
import std.math: approxEqual; assert(approxEqual(kelvinToCelsius(21.0), -252.15)); assert(approxEqual(kelvinToFahrenheit(21.0), -421.87)); assert(approxEqual(kelvinToRankine(21.0), 37.8));
}
void main(string[] args) {
import std.stdio, std.conv, std.string;
if (args.length == 2 && isNumeric(args[1])) {
immutable kelvin = to!double(args[1]);
if (kelvin >= 0) {
writefln("K %2.2f", kelvin);
writefln("C %2.2f", kelvinToCelsius(kelvin));
writefln("F %2.2f", kelvinToFahrenheit(kelvin));
writefln("R %2.2f", kelvinToRankine(kelvin));
} else
writefln("%2.2f K is below absolute zero", kelvin);
}
}</lang>
- Output:
K 21.00 C -252.15 F -421.87 R 37.80
J
Solution:<lang j> NB. Temp conversions are all linear polynomials
K2K =: 0 1 NB. K = (1 *k) + 0 K2C =: _273 1 NB. C = (1 *k) - 273 K2F =: _459.67 1.8 NB. F = (1.8*k) - 459.67 K2R =: 0 1.8 NB. R = (1.8*k) + 0
NB. Do all conversions at once (eval NB. polynomials in parallel). This is the NB. numeric matrix J programs would manipulate NB. directly. k2KCFR =: (K2K , K2C , K2F ,: K2R) p./ ]</lang>
Example:<lang j> NB. Format matrix for printing
fmt =: '0.2' 8!:0 k2KCFR
NB. Tag each temp with scale, for human NB. legibility. kcfr =: 0 _1 |: 'KCFR' ,"0 1"_1 >@:fmt kcfr 21
K 21.00 C-252.00 F-421.87 R 37.80
kcfr 0 NB. Absolute zero
K 0.00 C-273.00 F-459.67 R 0.00
kcfr 21 100 300 NB. List of temps works fine
K 21.00 C-252.00 F-421.87 R 37.80
K 100.00 C-173.00 F-279.67 R 180.00
K 300.00 C 27.00 F 80.33 R 540.00
</lang>
Notes: The approach is founded on polynomials, one for each conversion (e.g. Fahrenheit = 1.8*x - 459.67 where x is measured in degrees Kelvin), and all polynomials are evaluated simultaneously using the built-in p.. Through some code decorations (specifically the / in p./ the "0 1"_1 and the 0 _1 |:), we permit our function to convert arrays of temperatures of arbitrarily high dimension (a single temp, lists of temps, tables of temps, cubes of temps, etc).
Java
<lang java>public class TemperatureConversion {
public static void main(String args[]) {
if (args.length == 1) {
try {
double kelvin = Double.parseDouble(args[0]);
if (kelvin >= 0) {
System.out.printf("K %2.2f\n", kelvin);
System.out.printf("C %2.2f\n", kelvinToCelcius(kelvin));
System.out.printf("F %2.2f\n", kelvinToFahrenheit(kelvin));
System.out.printf("R %2.2f\n", kelvinToRankine(kelvin));
} else {
System.out.printf("%2.2f K is below absolute zero", kelvin);
}
} catch (NumberFormatException e) {
System.out.println(e);
}
}
}
public static double kelvinToCelcius(double k) {
return k + 273.15;
}
public static double kelvinToFahrenheit(double k) {
return k * 1.8 - 459.67;
}
public static double kelvinToRankine(double k) {
return k * 1.8;
}
}</lang>
K 21.00 C -252.15 F -421.87 R 37.80
PHP
<lang php>error_reporting(E_ALL & ~ ( E_NOTICE | E_WARNING ));
while (true) {
echo "\nEnter a value in kelvin (q to quit): ";
if (($kelvin = trim(fgets(STDIN))) !== false) {
if ($kelvin == 'q') {
echo 'quitting';
break;
}
if (is_numeric($kelvin)) {
$kelvin = floatVal($kelvin);
if ($kelvin >= 0) {
printf(" K %2.2f\n", $kelvin);
printf(" C %2.2f\n", $kelvin - 273.15);
printf(" F %2.2f\n", $kelvin * 1.8 - 459.67);
printf(" R %2.2f\n", $kelvin * 1.8);
} else printf(" %2.2f K is below absolute zero\n", $kelvin);
}
}
}</lang>
Enter a value in kelvin (q to quit): 21 K 21.00 C -252.15 F -421.87 R 37.80 Enter a value in kelvin (q to quit): q quitting
Python
<lang python>>>> while True: k = float(input('K ? ')) print("%g Kelvin = %g Celsius = %g Fahrenheit = %g Rankine degrees." % (k, k - 273.15, k * 1.8 - 459.67, k * 1.8))
K ? 21.0
21 Kelvin = -252.15 Celsius = -421.87 Fahrenheit = 37.8 Rankine degrees.
K ? 222.2
222.2 Kelvin = -50.95 Celsius = -59.71 Fahrenheit = 399.96 Rankine degrees.
K ? </lang>
Python: Universal conversion
This converts from any one of the units to all the others <lang python>>>> toK = {'C': (lambda c: c + 273.15),
'F': (lambda f: (f + 459.67) / 1.8),
'R': (lambda r: r / 1.8),
'K': (lambda k: k) }
>>> while True: magnitude, unit = input('<value> <K/R/F/C> ? ').split() k = toK[unit](float(magnitude)) print("%g Kelvin = %g Celsius = %g Fahrenheit = %g Rankine degrees." % (k, k - 273.15, k * 1.8 - 459.67, k * 1.8))
<value> <K/R/F/C> ? 222.2 K
222.2 Kelvin = -50.95 Celsius = -59.71 Fahrenheit = 399.96 Rankine degrees.
<value> <K/R/F/C> ? -50.95 C
222.2 Kelvin = -50.95 Celsius = -59.71 Fahrenheit = 399.96 Rankine degrees.
<value> <K/R/F/C> ? -59.71 F
222.2 Kelvin = -50.95 Celsius = -59.71 Fahrenheit = 399.96 Rankine degrees.
<value> <K/R/F/C> ? 399.96 R
222.2 Kelvin = -50.95 Celsius = -59.71 Fahrenheit = 399.96 Rankine degrees.
<value> <K/R/F/C> ? </lang>
REXX
This REXX version supports:
- (alternate spellings with optional degrees):
- Centingrade, centesimal, Celsius, Celcius
- Delisle
- Fahrenheit
- Kelvin
- Newton
- Rankine
- Reaumur, Réaumur
- Romer (Rømer), Roemer
- multiple temperatures in a list
- comments within the list
- aligned output (whole numbers and decimal fractions)
<lang rexx>/*REXX program converts temperature for: C, D, F, N, Ra, Re, Ro, and K.*/ parse arg tList /*get specified temperature lists*/
do until tList= /*process a list of temperatures.*/
parse var tList x ',' tList /*temps are separated by commas. */
x=space(x); parse var x z '(' /*handle any comments (if any). */
if z== then call serr 'no arguments were specified.'
_=verify(z, '+-.0123456789') /*a list of valid number thingys.*/
if _\==0 then do
if _==1 then call serr 'illegal temperature:' #
n=left(z,_-1) /*pick off the number (hopefully)*/
u=strip(substr(z,_)) /*pick off the temperature unit. */
end
else u='k' /*assume Kelvin as per task req.*/
uU=translate(u,'EE',"éÉ"); upper uU /*uppercase version of temp unit.*/
if left(uU,7)=='DEGREES' then uU=substr(uU,8) /*redundant "degrees"? */
if left(uU,5)=='DEGREE' then uU=substr(uU,7) /* " "degree" ? */
uU=strip(uU)
if \datatype(n,'N') then call serr 'illegal number:' n
/*accept alternate spellings. */
select /*convert ──► ºF temperatures. */
when abbrev('CENTIGRADE', uU) |,
abbrev('CENTESIMAL', uU) |,
abbrev('CELSIUS' , uU) |,
abbrev('CELCIUS' , uU) then F=n * 9/5 + 32
when abbrev('DELISLE' , uU) then F=212 -(n * 6/5)
when abbrev('FAHRENHEIT', uU) then F=n
when abbrev('KELVIN' , uU) then F=n * 9/5 - 459.67
when abbrev('NEWTON' , uU) then F=n * 60/11 + 32
when abbrev('RANKINE' , uU) then F=n - 459.67
when abbrev('REAUMUR' , uU, 2) then F=n * 9/4 + 32
when abbrev('ROEMER' , uU, 2) |,
abbrev('ROMER' , uU, 2) then F=(n-7.5) * 27/4 + 32
otherwise call serr 'illegal temperature scale:' u
end /*select*/
say right(' ' x,55,"─")
say Tform( ( F - 32 ) * 5/9 ) 'Celcius'
say Tform( ( 212 - F ) * 5/6 ) 'Delisle'
say Tform( F ) 'Fahrenheit'
say Tform( ( F + 459.67 ) * 5/9 ) 'Kelvin'
say Tform( ( F - 32 ) * 11/60 ) 'Newton'
say Tform( F + 459.67 ) 'Rankine'
say Tform( ( F - 32 ) * 4/9 ) 'Reaumur'
say Tform( ( F - 32 ) * 7/24 + 7.5 ) 'Romer'
end /*until tlist=*/
exit /*stick a fork in it, we're done.*/ /*──────────────────────────────────TFORM subroutine────────────────────*/ Tform: procedure; showDig=3; _=format(arg(1),,showDig)/1; p=pos('.',_) if p==0 then _=_ || left(,showDig+1)
else _=_ || left(,showDig-length(_)+p); return right(_,20)
/*──────────────────────────────────SERR subroutine─────────────────────*/ serr: say; say '***error!***'; say; say arg(1); say; exit 13</lang> output when using the input of: -40C, 0 c (water freezes), 37C (body temp), 100 C (water boils), 21 degrees Kelvin, 0K (outer space?)
───────────────────────────────────────────────── -40C
-40 Celcius
210 Delisle
-40 Fahrenheit
233.15 Kelvin
-13.2 Newton
419.67 Rankine
-32 Reaumur
-13.5 Romer
─────────────────────────────────── 0c (water freezes)
0 Celcius
150 Delisle
32 Fahrenheit
273.15 Kelvin
0 Newton
491.67 Rankine
0 Reaumur
7.5 Romer
────────────────────────────────────── 37C (body temp)
37 Celcius
94.5 Delisle
98.6 Fahrenheit
310.15 Kelvin
12.21 Newton
558.27 Rankine
29.6 Reaumur
26.925 Romer
─────────────────────────────────── 100c (water boils)
100 Celcius
0 Delisle
212 Fahrenheit
373.15 Kelvin
33 Newton
671.67 Rankine
80 Reaumur
60 Romer
──────────────────────────────────── 21 degrees Kelvin
-252.15 Celcius
528.225 Delisle
-421.87 Fahrenheit
21 Kelvin
-83.21 Newton
37.8 Rankine
-201.72 Reaumur
-124.879 Romer
──────────────────────────────────── 0K (outer space?)
-273.15 Celcius
559.725 Delisle
-459.67 Fahrenheit
0 Kelvin
-90.14 Newton
0 Rankine
-218.52 Reaumur
-135.904 Romer
[Actually, water freezes at 0.000089 ºC, and boils at 99.974 ºC.]