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Sierpinski curve: Difference between revisions
→{{header|Nim}}
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</lang>
=={{header|Nim}}==
{{trans|C++}}
We produce a SVG file using same algorithm as the one of C++ version.
<lang Nim>import math
type
SierpinskiCurve = object
x, y: float
angle: float
length: int
file: File
proc line(sc: var SierpinskiCurve) =
let theta = degToRad(sc.angle)
sc.x += sc.length.toFloat * cos(theta)
sc.y -= sc.length.toFloat * sin(theta)
sc.file.write " L", sc.x, ',', sc.y
proc execute(sc: var SierpinskiCurve; s: string) =
sc.file.write 'M', sc.x, ',', sc.y
for c in s:
case c
of 'F', 'G': sc.line()
of '+': sc.angle = floorMod(sc.angle + 45, 360)
of '-': sc.angle = floorMod(sc.angle - 45, 360)
else: discard
func rewrite(s: string): string =
for c in s:
if c == 'X':
result.add "XF+G+XF--F--XF+G+X"
else:
result.add c
proc write(sc: var SierpinskiCurve; size, length, order: int) =
sc.length = length
sc.x = length.toFloat / sqrt(2.0)
sc.y = 2 * sc.x
sc.angle = 45
sc.file.write "<svg xmlns='http://www.w3.org/2000/svg' width='", size, "' height='", size, "'>\n"
sc.file.write "<rect width='100%' height='100%' fill='white'/>\n"
sc.file.write "<path stroke-width='1' stroke='black' fill='none' d='"
var s = "F--XF--F--XF"
for _ in 1..order: s = s.rewrite()
sc.execute(s)
sc.file.write "'/>\n</svg>\n"
let outfile = open("sierpinski_curve.svg", fmWrite)
var sc = SierpinskiCurve(file: outfile)
sc.write(545, 7, 5)
outfile.close()</lang>
=={{header|Mathematica}} / {{header|Wolfram Language}}==
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