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>... > Please, > Could any of you find the numerical solution to the integral of sin[(xpi)/sqrt(x)] from pi/100 to pi? > > S = int(sin((xpi)/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((xpi)./sqrt(x)) quad(f,pi/100,pi,eps)
ans =
1.295458003695058

