이것이 왜 필요할까요?
어떤 분이 질문하셨던 문제입니다.
if you want to have this excel file...
it's free for your study.
let me think a ball(unit sphere, r=1)
if you choose random latitudes and random longitudes
it will result in an uneven distribution,
with the density increasing as we get closer to the poles.
So I want make a map.this will be easy for even a student to understand.
if there is a ball. which r=1
, the circle is as long as 2π
if you choose a point on surface, which has θ in latitudes
the horizontal diameter will be cosθ
and the new circle which the the point will have a length 2πcosθ
if you spread the surface of the ball flat, while maintain the area.
you will get this picture,
this is a identical to cosθ curve actually.
Now choose several points randomly
Point A is in red which means out of the Ball
Point B is in blue which means on the surface of the Ball
we will take Point B
and ignore Point A
let me thick, Point X
if Point X =(x, y)
you will get this picture.
Can you get latitudes and random longitudes?
it is easy enough, a school test.
YOU can get