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Thread Subject:
lenght of a sine curve

Subject: lenght of a sine curve

From: deepak

Date: 12 Jul, 2010 19:15:44

Message: 1 of 3

hi,

I have to measure the exact length of a sine curve say

a*sin(b*x)

from point x1 to x2.

Can you please tell me how can i do that.
I've tried quad and also tried to get implicit integral using symbolic but it's npt working.

Thanks

deepak

Subject: lenght of a sine curve

From: mt

Date: 12 Jul, 2010 19:40:22

Message: 2 of 3

On Jul 12, 3:15 pm, "deepak " <dkjkno...@rediff.com> wrote:
> hi,
>
> I have to measure the exact length of a sine curve say
>
> a*sin(b*x)
>
> from point x1 to x2.
>
> Can you please tell me how can i do that.
> I've tried quad and also tried to get implicit integral using symbolic but it's npt working.
>
> Thanks
>
> deepak

you can find more information on this problem here.

http://autarkaw.wordpress.com/2008/06/18/finding-the-length-of-curve-using-matlab/

Subject: lenght of a sine curve

From: Roger Stafford

Date: 12 Jul, 2010 20:06:04

Message: 3 of 3

"deepak " <dkjknobel@rediff.com> wrote in message <i1fpl0$eih$1@fred.mathworks.com>...
> hi,
>
> I have to measure the exact length of a sine curve say
>
> a*sin(b*x)
>
> from point x1 to x2.
>
> Can you please tell me how can i do that.
> I've tried quad and also tried to get implicit integral using symbolic but it's npt working.
>
> Thanks
>
> deepak
- - - - - - - - -
  Your problem leads to an incomplete elliptic integral, so you had better use numerical integration techniques. What is your problem with quad? You need to evaluate the integral

 int(from x = x1 to x = x2 of sqrt(1+a^2*b^2*cos(b*x)^2) w.r. x

The function quad, quadl, or quadgk should handle that very nicely.

Roger Stafford

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