Convex hull: Difference between revisions
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{{out}}
<pre>Convex Hull: [(-9, -3), (-3, -9), (19, -8), (17, 5), (12, 17), (5, 19), (-3, 15)]</pre>
=={{header|EasyLang}}==
{{trans|Nim}}
<syntaxhighlight>
func orientation p[] q[] r[] .
return (q[2] - p[2]) * (r[1] - q[1]) - (q[1] - p[1]) * (r[2] - q[2])
.
proc calcConvexHull . pts[][] res[][] .
res[][] = [ ]
indMinX = 1
for i to len pts[][]
if pts[i][1] < pts[indMinX][1]
indMinX = i
.
.
p = indMinX
repeat
res[][] &= pts[p][]
q = (p + 1) mod1 len pts[][]
for i to len pts[][]
if orientation pts[p][] pts[i][] pts[q][] < 0
q = i
.
.
p = q
until p = indMinX
.
.
#
pts[][] = [ [ 16 3 ] [ 12 17 ] [ 0 6 ] [ -4 -6 ] [ 16 6 ] [ 16 -7 ] [ 16 -3 ] [ 17 -4 ] [ 5 19 ] [ 19 -8 ] [ 3 16 ] [ 12 13 ] [ 3 -4 ] [ 17 5 ] [ -3 15 ] [ -3 -9 ] [ 0 11 ] [ -9 -3 ] [ -4 -2 ] [ 12 10 ] ]
calcConvexHull pts[][] res[][]
print res[][]
</syntaxhighlight>
{{out}}
<pre>
[
[ -9 -3 ]
[ -3 -9 ]
[ 19 -8 ]
[ 17 5 ]
[ 12 17 ]
[ 5 19 ]
[ -3 15 ]
]
</pre>
=={{header|F_Sharp|F#}}==
Line 6,985 ⟶ 7,030:
{{libheader|Wren-trait}}
{{libheader|Wren-iterate}}
<syntaxhighlight lang="
import "./trait" for Comparable
import "./iterate" for Stepped
class Point is Comparable {
Line 7,041 ⟶ 7,086:
Convex Hull: [(-9, -3), (-3, -9), (19, -8), (17, 5), (12, 17), (5, 19), (-3, 15)]
</pre>
=={{header|XPL0}}==
<syntaxhighlight lang "XPL0">func real CosAng(A, B); \Return cosine of angle between vectors A and B
int A, B; \Cos(Ang) = DotProd / (|A|*|B|)
real DotProd, Magnitude;
[DotProd:= float( A(0)*B(0) + A(1)*B(1));
Magnitude:= sqrt(float( sq(B(0)-A(0)) + sq(B(1)-A(1)) ));
return DotProd / Magnitude;
];
proc ConvexHull(N, P);
int N, P;
int Min, I, HullI, EndI, A(2), B(2), J, SJ;
real Ang, MinAng;
[Min:= -1>>1; \find index of point with smallest X coordinate
for I:= 0 to N-1 do
if P(I,0) < Min then
[Min:= P(I,0); HullI:= I];
EndI:= HullI;
A(0):= 0; A(1):= -1;
repeat ChOut(0, ^();
IntOut(0, P(HullI,0)); ChOut(0, ^,); IntOut(0, P(HullI,1));
ChOut(0, ^));
MinAng:= -1e12; \find index of point with smallest diverting angle
for J:= 0 to N-1 do
[B(0):= P(J,0) - P(HullI,0); B(1):= P(J,1) - P(HullI,1);
Ang:= CosAng(A, B);
if Ang > MinAng and J # HullI then
[MinAng:= Ang; SJ:= J];
];
A(0):= P(SJ,0) - P(HullI,0); A(1):= P(SJ,1) - P(HullI,1);
HullI:= SJ;
if HullI # EndI then Text(0, ", ");
until HullI = EndI;
];
ConvexHull(20, [[16,3], [12,17], [0,6], [-4,-6], [16,6], [16,-7], [16,-3],
[17,-4], [5,19], [19,-8], [3,16], [12,13], [3,-4], [17,5],
[-3,15], [-3,-9], [0,11], [-9,-3], [-4,-2], [12,10]])
</syntaxhighlight>
{{out}}
<pre>
(-9,-3), (-3,-9), (19,-8), (17,5), (12,17), (5,19), (-3,15)</pre>
=={{header|zkl}}==
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