Hi all. I am new to this list ;) Today I have encountered something new that has never happened to me in the past 6 months that I have been using ghci and Haskell.
I wrote this function:
type Line = (Point,Point)
type Point = (Float,Float)
circleLineIntersection :: Float -> Float -> Float -> Line -> Maybe [Point]
circleLineIntersection h k r ((x1,y1),(x2,y2)) = do
let
perpdist = calcPerpDist (h,k) ((x1,y1),(x2,y2))
noSolution = perpdist > r
oneSolution = perpdist == r
twoSolutions = perpdist < r
in
do
if noSolution then
Nothing
else
let
dx = x2 - x1
dy = y2 - y1
dr = sqrt (dx * dx + dy * dy)
bigD = x1 * y2 - x2 * y1
x1 = ( bigD * dy + sign (dy) * dx * sqrt( r * r * dr * dr - bigD * bigD ) ) / (dr * dr)
y1 = - bigD * dx + abs(dy) * sqrt( r * r * dr * dr - bigD * bigD ) / (dr * dr)
x2 = ( bigD * dy - sign (dy) * dx * sqrt( r * r * dr * dr - bigD * bigD ) ) / (dr * dr)
y2 = - bigD * dx - abs(dy) * sqrt( r * r * dr * dr - bigD * bigD ) / (dr * dr)
in
if oneSolution then
do
Just [(x1,y1)]
else
do
Just [(x1,y1),(x2,y2)]
Compiling is fine...
When I run the function like this....
circleLineIntersection 1 1 1 ((1,1),(2,2))
it simply outputs....
Just [(
No CPU usage.
I am using fglasgow-exts
Thanks for your help.
Gaetano