Help needed about numerical integration in matlab
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From: Muhammad on 27 Jul 2010 09:44 "Muhammad " <mtornado16(a)hotmail.com> wrote in message <i2mn8s$hrv$1(a)fred.mathworks.com>... > "us " <us(a)neurol.unizh.ch> wrote in message <i2mmef$mua$1(a)fred.mathworks.com>... > > "Muhammad " > > > Sorry for my mistake. Yes you are right .... x is defined as > > > > > > syms x ; > > > > > > Please give any suggestion how to evaluate this integral ..... > > > > > > Thanks > > > > according to the title of your OP, you're looking for numerical integration... > > since INT() works on syms, you'd have to look into other ML functions, eg, > > > > help quad; % <- and its many siblings... > > > > us > > > Thanks for reply. But quad() and its versions work on scalar limits of integration but I have to evaluate the integral from a positive scalar to infinity. ??? Anyhow I have tried to put a large number instead of infinity to evaluate integral ... but now the error goes like: ??? Error using ==> mpower Matrix must be square. Error in ==> @(x)(x/(2*l*s))^0.5*(l-1)*(exp(-0.5*(x+2*l*s)))*besseli(l,sqrt(2*l*s*x))*gammainc(x,l)^(N-1) Error in ==> quad at 77 y = f(x, varargin{:}); Error in ==> reference_strat_roc at 26 pd = 0.5 * quad(ff,b,1e100); any comments ???
From: Steven_Lord on 27 Jul 2010 10:50
"Muhammad " <mtornado16(a)hotmail.com> wrote in message news:i2mn8s$hrv$1(a)fred.mathworks.com... > "us " <us(a)neurol.unizh.ch> wrote in message > <i2mmef$mua$1(a)fred.mathworks.com>... >> "Muhammad " >> > Sorry for my mistake. Yes you are right .... x is defined as >> > >> > syms x ; >> > >> > Please give any suggestion how to evaluate this integral ..... >> > >> > Thanks >> >> according to the title of your OP, you're looking for numerical >> integration... >> since INT() works on syms, you'd have to look into other ML functions, >> eg, >> >> help quad; % <- and its many siblings... >> >> us > > > Thanks for reply. But quad() and its versions work on scalar limits of > integration but I have to evaluate the integral from a positive scalar to > infinity. ??? QUAD requires finite limits of integration. QUADGK does not. Also remember that both QUAD and QUADGK will call your function with a _vector_ as input, so you may need to use elementwise operations (like .*, ./, .\, or .^) instead of the matrix operations (*, /, \, or ^) in your integrand function. -- Steve Lord slord(a)mathworks.com comp.soft-sys.matlab (CSSM) FAQ: http://matlabwiki.mathworks.com/MATLAB_FAQ To contact Technical Support use the Contact Us link on http://www.mathworks.com |