Date: Jan 13, 2013 5:14 PM
Author: Derek Goring
Subject: Re: how to find x for given y
On Monday, January 14, 2013 10:14:38 AM UTC+13, johnyyy wrote:

> Hi everyone!

>

> I have a problem with matlab. I was trying to find the answer in the Internet, but I didn't.

>

> dx/dt=sin(x), x(0)=0.5. I have to find time when x=1.5 (t(x=1.5)=?). Can anybody help me, please:)

Sounds like homework, and pretty simple homework at that.

I don't know what you problem with Matlab is, because it really doesn't require Matlab

dx/dt=sin(x)

so, from Abramowitz & Stegun, the integral of cosec(x) is:

t=const + 0.5*log((1-cos(x))/(1+cos(x))

Now, just substitute x=0.5 and evaluate the const for t=0

Then, substitute for x