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Topic: problems integrating a function
Replies: 5   Last Post: Jan 5, 2011 11:38 AM

 Messages: [ Previous | Next ]
 proecsm Posts: 106 Registered: 1/30/10
Re: problems integrating a function
Posted: Jan 4, 2011 9:18 PM

"Marcio Barbalho" wrote in message <ig0hh0\$pvb\$1@fred.mathworks.com>...
> Could any of you find the numerical solution to the integral of sin[(x-pi)/sqrt(x)] from pi/100 to pi?
>
> S = int(sin((x-pi)/sqrt(x)),x=pi/100..pi)
>
> You may copy and paste there.
> I have already tried both Matlab and Scilab.
>
> From Matlab I get:
> Warning: Explicit integral could not be found.

> > In sym.int at 64
> In char.int at 9
> ans =
> int(-sin(1/x^(1/2)*(pi - x)), x = pi/100..pi)
>
> From scilab (I installed scilab just to integrate this function):
> -->integrate('sin((x-%pi)/sqrt(x))','x',0,%pi)
> !--error 24
> Convergence problem...
> at line 70 of function integrate called by :
> integrate('sin((x-%pi)/sqrt(x))','x',0,%pi)
>
> The solution is -1.295820
>
> I just can't get Matlab to find it.
>
> Many thanks

It does not have a closed from solution, here is numeric

f = @(x)sin((x-pi)./sqrt(x))

ans =

-1.295458003695058

Date Subject Author
1/4/11 Marcio Barbalho
1/4/11 Oleg Komarov
1/4/11 proecsm
1/5/11 Walter Roberson
1/5/11 Greg von Winckel
1/5/11 Greg von Winckel