Display Scrolling Waves

Question

The challenge is to display and scroll a sine waveform in the least number of characters.

Restrictions:

• Total height of wave must be at least seven units (characters, pixels, etc).
• The generated wave must scroll in-place.

Additional Rules/Information:

• The sine wave must be distinguishable from triangle and square waves.
  • "distinguishable" indicates sampling at least every π/8

Additional Judgement Criteria:

• Appearance/Quality of the wave
• Number of periods displayed

Winning entries will have the fewest characters of code and generate a sine wave with the most samples per period.

Answer 1

APL (46)

{∇⍵+1⊣⎕DL÷9⊣⎕SM∘←↑⍵∘{0,⍵,⍨9+⌈9×1○9÷⍨⍺+⍵}¨⍳79}1

It looks like this, and scrolls to the left:

In action: http://frankenstein.d-n-s.org.uk/~marinus/sine.mp4

Answer 2

Mathematica : 49

Plot[Sin[x+a],{x,0,9},Axes->None]~Animate~{a,0,2Pi}

The flickering is a GIF-produced artifact. Runs smoothly on the screen.

Answer 3

Machine code x86 16-bit DOS, 40 bytes

░‼═►h áë←☺‼▀♥▐4┘■▐♀▐♦▀←i;@☺&ê◄■├uσBδ╪

Or in a more human readable format (typical hugi conventions followed) :

;  40 byte version
; 00000000:  0A 00 B0 13 CD 10 68 00-A0 07 89 1B 01 13 DF 03   ......h.........
; 00000010:  DE 34 D9 FE DE 0C DE 04-DF 1B 69 3B 40 01 26 88   .4........i;@.&.
; 00000020:  11 FE C3 75 E5 42 EB D8                           ...u.B..

;  42 byte version
; 00000000:  0A 00 B0 13 CD 10 68 00-A0 07 89 1B 01 13 DF 03   ......h.........
; 00000010:  DE 34 D9 FE DE 0C DE 04-DF 1B 69 3B 40 01 26 88   .4........i;@.&.
; 00000020:  11 FE C3 75 E5 42 E2 FE-EB D6                     ...u.B....

[bits 16]


newscreen:
 or al,[bx+si]  ; trade off vertical height for # of periods
 mov al,13h
 int 10h
 push 0a000h
 pop es


iter:
 mov word [bp+di],bx
 add word [bp+di],dx
 fild word [bp+di]
 fidiv word [si]
 fsin
 fimul word [si]
 fiadd word [si]
 fistp word [bp+di]
 imul di,word [bp+di],320
 mov [es:di+bx],dl
 inc bl
 jnz iter
 inc dx


delay:
 loop delay  ; can remove this to get 40 bytes, but wont look as good since it scrolls too fast

 jmp newscreen

Answer 4

Python 2.7 with Pygame (196 178)

import math,pygame as p
D=p.display
x=0
s=D.set_mode((600,400))
while 1:
 i=0;x+=1;D.flip();s.fill([0]*3)
 while i<600:s.set_at((i,int(200*math.sin((i+x)*.01)+200)),[255]*3);i+=1

Draws in pixels. Went for looks rather than characters.

Answer 5

Ruby, 105 characters

d=0
loop{s=(1..9).map{" "*79}
79.times{|i|s[(Math.sin((i+d)*Math::PI/16)*4+4.5)][i]=?x}
puts"^[[H",s
d+=1}

The ^[ is a single escape character. (You can enter it with Ctrl-V,Esc in the terminal and Vim or Ctrl-Q,Esc in MCEdit and Emacs.)

The animation is displayed from the 2^nd line of top left corner of the terminal and scrolls from right to left at full speed (add sleep 0.1; before the last } to slow it down).

Sample run:

bash-4.4$ ruby -e 'd=0;loop{s=(1..9).map{" "*79};79.times{|i|s[(Math.sin((i+d)*Math::PI/16)*4+4.5)][i]=?x};puts"^[[H",s;d+=1}'
                      xxxxx                           xxxxx                    
                    xx     xx                       xx     xx                  
                  xx         xx                   xx         xx                
                 x             x                 x             x               
x               x               x               x               x              
 x             x                 x             x                 x             
  xx         xx                   xx         xx                   xx         xx
    xx     xx                       xx     xx                       xx     xx  
      xxxxx                           xxxxx                           xxxxx    

Ruby: 115 characters

d=0
while 1
s=(1..9).map{" "*79}
79.times{|i|s[(Math.sin((i+d)*Math::PI/16)*4+4.5)][i]=?x}
$><<"\e[H"+s*$/
d+=1
end

The animation is displayed in the top left corner of the terminal and scrolls from right to left at full speed (add sleep 0.1; before the end keyword to slow it down).

Sample run:

                      xxxxx                           xxxxx
                    xx     xx                       xx     xx
                  xx         xx                   xx         xx
                 x             x                 x             x
x               x               x               x               x
 x             x                 x             x                 x
  xx         xx                   xx         xx                   xx         xx
    xx     xx                       xx     xx                       xx     xx
      xxxxx                           xxxxx                           xxxxx
bash-4.1$ ruby -e 'd=0;while 1;s=(1..9).map{" "*79};79.times{|i|s[(Math.sin((i+d)*Math::PI/16)*4+4.5)][i]=?x};$><<"\e[H"+s*$/;d+=1;end'

(I know, can be shortened by replacing Math::PI/16 with its precalculated value of arbitrary precision. For example to 107 characters by using 0.2 multiplier. But the lower the precision, the uglier the output. May edit it in the future, I just keep it for now.)

Answer 6

q

Quick and very ugly, 119 characters:

o:0;
w:.:["\\c"]1;
.z.ts:{-1@'{@[w#" ";where x=y;:;"0"]}[4-7h$4*sin o rotate(til w)%2*acos -1]'[til 9];o::o+1};
\t 100

Answer 7

Processing, 99

Really just a butchered version of this.

float i,x,t;void draw(){clear();x=t+=0.02;for(i=0;i<75;ellipse(i++*5,50+sin(x+=0.418879)*25,3,3));}

Try it online!

Could've saved some characters at the cost of an uglier animation. Slightly more readable form:

float i,x,t;

void draw() {
    clear();
    x = t+=0.02;
    for(i=0; i<75; ellipse(i++*5, 50+sin(x+=0.418879)*25, 3, 3));
}

Magic numbers:

• 0.02 kinda affects the scroll speed
• 75 is the number of dots
• 5 is the distance on x-axis
• 50 is the y-position on screen (default window size is 100).
• 0.418879 ≈ 2π/75*5
• 25 is the amplitude
• 3 is the size of the dots

Answer 8

C (65)

main(int x){for(;;)printf("%*c\n",(int)(22+20*sin(x++/5.)),'x');}

Note: plots sine wave with X axis vertical and therefore scrolls vertically.

Answer 9

Maple, 42 Characters

This is very easy to do with Maple.

plots[animate](plot,[sin(x+a)],a=0..2*Pi);

What it does

Answer 10

TI-BASIC, 22 bytes

• Name this prgmA. It eventually overflows the stack by calling itself, throwing an ERR:MEMORY; this can be rectified in exchange for 4 bytes by adding While 1 to the beginning and replacing the prgmA line with End.

• It works pretty much perfectly, although I'm afraid not much can be done to improve its speed.

• It's currently the winner by far, but can be 'golfed' to 18 bytes by removing the step argument (,.01) from the For( loop, lowering its "Number of periods displayed" score.

---

For(A,0,6,.01
ClrDraw
DrawF 7sin(X+A
End
prgmA

Answer 11

JavaScript: 265 characters + 59 HTML

<canvas id=c width=99 height=99></canvas>
<script>
var c=document.getElementById("c");var context=c.getContext("2d");context.beginPath();var s=0;setInterval(function(){c.width=c.width;s++;context.moveTo(0+50,50*Math.sin(s+0)+50);for(var e=1;e<99;e++){context.lineTo(e+50,50*Math.sin(s+50*e)+50)}context.stroke()},50)
</script>

JavaScript (ungolfed)

<canvas id="canvas" width="500" height="99"></canvas>
<script>
var c = document.getElementById("canvas");
var context = c.getContext("2d");
context.beginPath();
var s=0;
setInterval(function(){
    c.width = c.width;
    s++;
    context.moveTo(0+50,50*Math.sin(s+0)+50);
    for(var x=1;x<99;x++){
        context.lineTo(x+50, 50*Math.sin(s+50*x)+50);
    }
    context.stroke();
}, 50);
</script>

See it on http://jsfiddle.net/MartinThoma/uv5Xx/

Answer 12

Processing, 115 chars

This one actually draws a pseudo-sine wave, not an actual sine wave:

int t,i,c;void draw(){clear();beginShape();for(i=-1,c=50;i<6;c=-c)curveVertex(50*i++-t,50+c);endShape();t=t%100+1;}

A more readable version:

int t, i, c;
void draw() {
  clear();
  beginShape();
  for(i=-1, c=50; i<6; c=-c)
    curveVertex(50*i++ - t, 50+c);
  endShape();
  t = t%100 + 1;
}

Answer 13

SmileBASIC

The rules aren't entirely clear, so I'll post a few different answers:

34 bytes (vertical text):

LOCATE SIN(MILLISEC/9)*9+9,?.EXEC.

(It never specifically says this isn't allowed, but none of the other answers are vertical, so I'm not sure)

43 bytes (horizontal text):

LOCATE,SIN(MILLISEC/9)*9+9?0SCROLL-1,.EXEC.

53 bytes (horizontal graphics):

GPSET 1,SIN(MILLISEC/9)*9+9GCOPY.,0,#R,30,1,0,1
EXEC.

Answer 14

Mathematica, 38 bytes

Animate[Plot[Sin[x+a],{x,0,10}],{a,5}]

Non-competeting, uses Mathematica 10