Compute square root of a non negative number. This method is internally
used by Math.sqrt.
# File lib/mathn.rb, line 141
def rsqrt(a)
if a.kind_of?(Float)
sqrt!(a)
elsif a.kind_of?(Rational)
rsqrt(a.numerator)/rsqrt(a.denominator)
else
src = a
max = 2 ** 32
byte_a = [src & 0xffffffff]
# ruby's bug
while (src >= max) and (src >>= 32)
byte_a.unshift src & 0xffffffff
end
answer = 0
main = 0
side = 0
for elm in byte_a
main = (main << 32) + elm
side <<= 16
if answer != 0
if main * 4 < side * side
applo = main.div(side)
else
applo = ((sqrt!(side * side + 4 * main) - side)/2.0).to_i + 1
end
else
applo = sqrt!(main).to_i + 1
end
while (x = (side + applo) * applo) > main
applo -= 1
end
main -= x
answer = (answer << 16) + applo
side += applo * 2
end
if main == 0
answer
else
sqrt!(a)
end
end
end
