how to calculate the distance between the two point on the ellipse

ATC243750496

                       ***********************************************
                   ***                                                 ***
                **                                                         **
              *                                                               x1
            *                                                                   x
          *                                                                       x
         *                                                                         x                                                                       
         *                                                                         x  
          *                                                                       x
            *                                                                   x
              *                                                               x2
                **                                                         **
                   ***                                                 ***
                       ***********************************************

if i have the equation of ellipse (x/a^2+y/b^2=1),a,b and x’s coordinates is known now,how to calculate the the length of curve between the two point???

PhiLho

Why this isn't in the How To category, given the formulation of the subject?... Moved!

Looks more like a math question (assignment, likely) than a programming question... So that's not about Using Processing at all.

Perhaps you can use your Internet connection to Google about formulae giving the length of an arc?

ATC243750496

i found nothing about it and it's true that the problem is about math , but i am an art student , and don't have learn higher mathematics so i hope there's someone on the internet can slove this

koogs

do points 1 and 2 have the same value of x? i assume they so.

i'm not sure i trust that equation you posted in the form you have it.

(x / a) ^ 2 + (y / b) ^ 2 = 1

so, with some rearranging

y = b * sqrt(1 - ((x / a)^2))

so your distance will be twice that...

GoToLoop

y = b * sqrt(1 - ((x / a)^2))

I guess that'd be... :-B

float y = b*sqrt(1 - sq(x/a));

ATC243750496

sorry the value of x for two points doesn't same , and i want to get the distance between them ,witch is shown with the mark 'x'

PhiLho

How do you define which points you need? For a given x, you have two points on the ellipse.

blyk

http://www.oocities.org/web_sketches/ellipse_notes/ellipse_arc_length/ellipse_arc_length.html

ATC243750496

give the x and y(calculated from the equation of ellipse)

ATC243750496

closed