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Circles of given radius through two points: Difference between revisions
Circles of given radius through two points (view source)
Revision as of 06:26, 20 April 2013
, 11 years ago→{{header|REXX}}: added the REXX language. -- ~~~~
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You can construct the following circles:
ERROR: radius of zero</pre>
=={{header|REXX}}==
{{trans|xxx}}
<lang rexx>/*REXX pgm finds 2 circles with a specific radius given two (X,Y) points*/
@. =
@.1= 0.1234 0.9876 0.8765 0.2345 2
@.2= 0.0000 2.0000 0.0000 0.0000 1
@.3= 0.1234 0.9876 0.1234 0.9876 2
@.4= 0.1234 0.9876 0.8765 0.2345 0.5
@.5= 0.1234 0.9876 0.1234 0.9876 0
say ' x1 y1 x2 y2 radius cir1x cir1y cir2x cir2y'
say ' ──────── ──────── ──────── ──────── ────── ──────── ──────── ──────── ────────'
do j=1 while @.j\=='' /*process all given points&radius*/
do k=1 for 4; w.k=f(word(@.j,k)); end /*k*/ /*format num.*/
say w.1 w.2 w.3 w.4 center(word(@.j,5),9) "───► " twoCircles(@.j)
end /*j*/
exit /*stick a fork in it, we're done.*/
/*──────────────────────────────────F subroutine────────────────────────*/
f: return right(format(arg(1),,4),9) /*format a number with 4 dec dig.*/
/*──────────────────────────────────SQRT subroutine─────────────────────*/
sqrt: procedure; parse arg x; if x=0 then return 0; d=digits();numeric digits 11
g=.sqrtGuess(); do j=0 while p>9; m.j=p; p=p%2+1; end
do k=j+5 to 0 by -1; if m.k>11 then numeric digits m.k; g=.5*(g+x/g); end
numeric digits d; return g/1
.sqrtGuess: if x<0 then call sqrtErr; numeric form; m.=11; p=d+d%4+2
parse value format(x,2,1,,0) 'E0' with g 'E' _ .; return g*.5'E'_%2
/*──────────────────────────────────twoCircles subroutine───────────────*/
twoCircles: procedure; parse arg px py qx qy r .
if r=0 then return 'radius of zero gives no circles.'
x=(qx-px)/2; y=(qy-py)/2; bx=px+x; by=py+y; pb=sqrt(x**2+y**2)
if pb=0 then return 'coincident points give infinite circles'
if pb>r then return 'points are too far apart for the given radius'
cb=sqrt(r**2-pb**2); x1=y*cb/pb; y1=x*cb/pb
return f(bx-x1) f(by+y1) f(bx+x1) f(by-y1)</lang>
'''output''' when using the default input(s):
x1 y1 x2 y2 radius cir1x cir1y cir2x cir2y
──────── ──────── ──────── ──────── ────── ──────── ──────── ──────── ────────
0.1234 0.9876 0.8765 0.2345 2 ───► 1.8631 1.9742 -0.8632 -0.7521
0.0000 2.0000 0.0000 0.0000 1 ───► 0.0000 1.0000 0.0000 1.0000
0.1234 0.9876 0.1234 0.9876 2 ───► coincident points give infinite circles
0.1234 0.9876 0.8765 0.2345 0.5 ───► points are too far apart for the given radius
0.1234 0.9876 0.1234 0.9876 0 ───► radius of zero gives no circles.
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=={{header|Tcl}}==
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