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Sierpinski arrowhead curve: Difference between revisions
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Line 696:
lns = Nest[Catenate[DoStep /@ #] &, lns, 5];
Graphics[lns]</lang>
=={{header|Nim}}==
{{trans|C++}}
Output is an SVG file.
<lang Nim>import math
const Sqrt3_2 = sqrt(3.0) / 2.0
type Point = tuple[x, y: float]
func sierpinskiArrowheadNext(points: seq[Point]): seq[Point] =
result.setLen(3 * (points.len - 1) + 1)
var j = 0
for i in 0..<points.high:
let (x0, y0) = points[i]
let (x1, y1) = points[i + 1]
let dx = x1 - x0
result[j] = (x0, y0)
if y0 == y1:
let d = abs(dx * Sqrt3_2 / 2)
result[j + 1] = (x0 + dx / 4, y0 - d)
result[j + 2] = (x1 - dx / 4, y0 - d)
elif y1 < y0:
result[j + 1] = (x1, y0)
result[j + 2] = (x1 + dx / 2, (y0 + y1) / 2)
else:
result[j + 1] = (x0 - dx / 2, (y0 + y1) / 2)
result[j + 2] = (x0, y1)
inc j, 3
result[j] = points[^1]
proc writeSierpinskiArrowhead(outfile: File; size, iterations: int) =
outfile.write "<svg xmlns='http://www.w3.org/2000/svg' width='", size, "' height='", size, "'>\n"
outfile.write "<rect width='100%' height='100%' fill='white'/>\n"
outfile.write "<path stroke-width='1' stroke='black' fill='none' d='"
const Margin = 20.0
let side = size.toFloat - 2 * Margin
let x = Margin
let y = 0.5 * size.toFloat + 0.5 * Sqrt3_2 * side
var points = @[(x: x, y: y), (x: x + side, y: y)]
for _ in 1..iterations:
points = sierpinskiArrowheadNext(points)
for i, point in points:
outfile.write if i == 0: 'M' else: 'L', point.x, ',', point.y, '\n'
outfile.write "'/>\n</svg>\n"
let outfile = open("sierpinski_arrowhead.svg", fmWrite)
outfile.writeSierpinskiArrowhead(600, 8)
outfile.close()</lang>
{{out}}
See output of C++ program.
=={{header|Perl}}==
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