Re: NIntegrate with AdaptiveMonteCarlo gives different results
- To: mathgroup at smc.vnet.net
- Subject: [mg123338] Re: NIntegrate with AdaptiveMonteCarlo gives different results
- From: valentina <fuchi8 at tiscali.it>
- Date: Fri, 2 Dec 2011 07:20:40 -0500 (EST)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- References: <jb7u17$jr5$1@smc.vnet.net>
On Dec 1, 2:04 pm, valentina <fuc... at tiscali.it> wrote: > Hello everybody, > I am dealing with a three dimensional integral and I am using > NIntegrate. Searching the web I found out that the best method is the > AdaptiveMonteCarlo, which also speed up the calculation. > this is the integral, no particular singular points: > > test[d_] := (0.5 NIntegrate[(compnx[x, y, z, d] + > compny[x, y, z, d] + compnz[x, y, z, d]), {z, -R - d/2, > R + d/2}, {x, -R, R}, {y, -R, R}, > Method -> "MultiDimensionalRule"]*hc) // Timing > > so I want to calculate it for different values of the parameter d, but > for example if I successively calculate it for d=4 i get two different > results which differs of about 30-50 MeV. > > Does anyone know if it is a bug or how could I fix it? > > Thanks in advance. Sorry, I did not tell everything about the integrand. x,y,z are the Cartesian coordinate, so I am dealing with three dimensional functions, smooth function imagine like having two smooth peaks centered in a symmetric way around (0,0,0). Just when both x and y are equal to zero i have singularities but NIntegrate seems to deal with them because without specifying the method, it took hours, but i get the correct result. hc is a physical constant, namely 197.3 MeV fm, so it's a number just to have the result in energy dimension. Should I specify more options when calling the AdaptiveMonteCarlo? thanks and sorry again for my lack of informations