Shape-Machine

Shape-Machine is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Task

Get user input and then add 3, multiply that 0.86 and repeat forever. You can halt the loop and count how many times does the operation happen, this is optional

See Also

• Esolangs.org page

ALGOL 68

Non-terminating

Translation of: Python

BEGIN
    REAL a := BEGIN INT n; read( n ); n END;
    DO
        print( ( fixed( a +:= 3 *:= 0.86, -16, 14 ), newline ) )
    OD
END

Terminating after successive values converge

Based on Raku, using 64-bit floating point.

BEGIN
    REAL a      := BEGIN INT n; read( n ); n END;
    REAL prev a := IF a = 0 THEN 1 ELSE 0 FI;
    INT  count  := 0;
    WHILE prev a /= a
    DO
        count +:= 1;
        prev a := a;
        print( ( fixed( a +:= 3 *:= 0.86, -16, 14 ), newline ) )
    OD;
    print( ( whole( count, 0 ), " repetitions" ) )
END

Output:

With 4 as the input

6.02000000000000
7.75720000000000
9.25119200000000
10.5360251200000
11.6409816032000
12.5912441787520
13.4084699937267
14.1112841946050
...
18.3988095846536
18.4029762428021
18.4065595688098
...
18.4285714285714
18.4285714285714
18.4285714285714
231 repetitions

ALGOL W

Translation of: Python

begin
    real a;
    integer n;
    read( n );
    a := n;
    while true do begin
        a := a + 3;
        a := a * 0.86;
        write( r_format := "A", r_w := 8, r_d := 5, a )
    end
end.

Output:

With 4 as the input

 6.02000
 7.75720
 9.25119
10.53603
11.64098
12.59124
13.40847
14.11128
...
18.42857
18.42857
18.42857
...

jq

Works with jq, the C implementation of jq

Works with gojq, the Go implementation of jq

Works with jaq, the Rust implementation of jq

In accordance with the basic task description, here is a solution that does not terminate:

input | recurse(. + 3 | . * 0.86)

To examine the first five generated items, we could use the shell's `head` utility, e.g. as follows:

$ jq -n ' input | recurse(. + 3 | . * 0.86)' <<< 0 | head -n 5
0
2.58
4.7988
6.706968
8.34799248

Notice that the output of `recurse` includes the input value.

To limit the generator programmatically, one could use the `limit/2` built-in:

$ jq -n --argjson n 5 'input | limit($n; recurse(. + 3 | . * 0.86))' <<< 1
1
3.44
5.538399999999999
7.343023999999999
8.89500064

One way to suppress the first item produced by the generator would be to use `whilst/1`:

# like while/2 but emit the final term rather than the first one
def whilst(cond; update):
     def _whilst:
         if cond then update | (., _whilst) else empty end;
     _whilst;

input | whilst(true; . + 3 | .  * 0.86)

To stop when the generated number satisfies `trunc == 18`, one could use the following filter:

whilst(trunc != 18; . + 3 | .  * 0.86)

To determine how many iterations it takes until the truncated value is 18, one could use `until/2`:

$ jq -n '{i:input} | until(.i|trunc == 18; .i += 3 | .i *= 0.86 | .n+=1)' <<< 0
{
  "i": 18.003997862641942,
  "n": 25
}

Python

a=int(input())
while True:
    a += 3
    a *= 0.86
    print(a)

Raku

my $input = (+prompt()).FatRat;
my $previous = 0.FatRat;
my $count;
my $places = 36;
loop {
    $input += 3;
    $input ×= .86;
    last if $previous.substr(0,$places) eq $input.substr(0,$places);
    ++$count;
    say ($previous = $input).substr(0,$places);
}
say "$count repetitions";

Output with a 4 fed in at the prompt:

4
6.02
7.7572
9.251192
10.53602512
11.6409816032
12.591244178752
13.40846999372672
14.1112841946049792
14.715704407360282112
15.23550579032984261632
15.6825349796836646500352
16.066980082527951599030272

...
many, many lines omitted
...

18.428571428571428571428571428571416
18.428571428571428571428571428571418
18.428571428571428571428571428571419
18.428571428571428571428571428571420
18.428571428571428571428571428571421
18.428571428571428571428571428571422
18.428571428571428571428571428571423
18.428571428571428571428571428571424
512 repetitions

Wren

This repeats until the next number (a 64 bit float) equals the previous number which will usually be sometime later than their string/display values (normally limited to 14 digits in Wren CLI) are equal.

import "./ioutil" for Input

var prev = Input.number("")
var count = 1
while (true) {
    var next = (prev + 3) * 0.86
    if (prev == next) break
    System.print(prev = next)
    count = count + 1
}
System.print("Took %(count) iterations.")

Output:

Sample input/output (abridged):

4
6.02
7.7572
9.251192
10.53602512
11.6409816032
12.591244178752
13.408469993727
14.111284194605
14.71570440736
...
18.428571428571
18.428571428571
18.428571428571
18.428571428571
18.428571428571
18.428571428571
18.428571428571
18.428571428571
18.428571428571
18.428571428571
Took 231 iterations.

XPL0

Translation of: Python

real A;
[A:= RlIn(0);
while true do
    [A:= A+3.;
    A:= A*0.86;
    RlOut(0, A);
    ];
]

Output:

123
108.36000 95.76960 84.94186 75.63000 67.62180 60.73475 54.81188 49.71822
45.33767 41.57039 38.33054 35.54426 33.14807 31.08734 29.31511 27.79099
26.48026 25.35302 24.38360 23.54989 22.83291 22.21630 21.68602 21.22998
20.83778 20.50049 20.21042 19.96096 19.74643 19.56193 19.40326 19.26680
19.14945 19.04853 18.96173 18.88709 18.82290 18.76769 18.72022 18.67939
18.64427 18.61407 18.58810 18.56577 18.54656 18.53004 18.51584 18.50362
18.49311 18.48408 18.47631 18.46962 18.46388 18.45893 18.45468 18.45103
18.44788 18.44518 18.44285 18.44085 18.43914 18.43766 18.43638 18.43529
18.43435 18.43354 18.43285 18.43225 18.43173 18.43129 18.43091 18.43058
18.43030 18.43006 18.42985 18.42967 18.42952 18.42938 18.42927 18.42917
18.42909 18.42902 18.42895 18.42890 18.42885 18.42881 18.42878 18.42875
18.42873 18.42870 18.42869 18.42867 18.42866 18.42864 18.42863 18.42863
18.42862 18.42861 18.42861 18.42860 18.42860 18.42859 18.42859 18.42859
18.42859 18.42858 18.42858 18.42858 18.42858 18.42858 18.42858 18.42858
18.42858 18.42857 18.42857 18.42857 18.42857 18.42857 18.42857 18.42857
18.42857 18.42857 18.42857 18.42857 18.42857 18.42857 18.42857 18.42857
18.42857 18.42857 18.42857 18.42857 18.42857 18.42857 18.42857 18.42857