Thread Subject:

how do i unwrap 'arcsin' function?

Hi all!
    i've encountered a problem.As we know the range of 'arcsin' in matlab is -pi/2~pi/2.
if we do asin(sin(t)),t= 0:10;we get an wrap answer,but now i want to retrieve the 't',how can i get the original 't'? Thank you!

and we may also encouter such a problem about elliptic integral.For example .elliptic integral of third kind,and it's also period function.My question is how i can get a monotone function.

"flying" wrote in message <jqarl1$dkk$1@newscl01ah.mathworks.com>...
> Hi all!
> i've encountered a problem.As we know the range of 'arcsin' in matlab is -pi/2~pi/2.
> if we do asin(sin(t)),t= 0:10;we get an wrap answer,but now i want to retrieve the 't',how can i get the original 't'? Thank you!
========

You cannot, due to sin(t) not being 1-1.

"Matt J" wrote in message <jqb26t$dm0$1@newscl01ah.mathworks.com>...
> "flying" wrote in message <jqarl1$dkk$1@newscl01ah.mathworks.com>...
> > Hi all!
> > i've encountered a problem.As we know the range of 'arcsin' in matlab is -pi/2~pi/2.
> > if we do asin(sin(t)),t= 0:10;we get an wrap answer,but now i want to retrieve the 't',how can i get the original 't'? Thank you!
> ========
>
> You cannot, due to sin(t) not being 1-1.


the range of 't' is 0~10 and my target is retrieving 't'

On Saturday, June 2, 2012 4:46:25 AM UTC+12, flying wrote:
> Hi all!
> i've encountered a problem.As we know the range of 'arcsin' in matlab is -pi/2~pi/2.
> if we do asin(sin(t)),t= 0:10;we get an wrap answer,but now i want to retrieve the 't',how can i get the original 't'? Thank you!
>
> and we may also encouter such a problem about elliptic integral.For example .elliptic integral of third kind,and it's also period function.My question is how i can get a monotone function.

help unwrap

"flying" wrote in message <jqbvcq$d93$1@newscl01ah.mathworks.com>...
>
> > You cannot, due to sin(t) not being 1-1.
>
>
> the range of 't' is 0~10 and my target is retrieving 't'
==============

It is a target you will not be able to achieve.
sin(t) is not 1-1 on the interval 0<=t<=10