On Sat, Apr 13, 2013 at 6:31 AM, peter dalgaard <pdalgd@gmail.com> wrote:

> But is it supposed to be t^{-3/2} or t^{-0.5}?? The formula has the former
> and the code the latter, and the integral is clearly divergent with the
> former.
>


I didn't look at that -- I just assumed that the code would reproduce the
reported error.

    -thomas



> -pd
>
> On Apr 12, 2013, at 04:51 , Thomas Lumley wrote:
>
> > I don't get an error message (after I correct the missing line break
> after
> > the comment
> >
> >> b<- sapply(a, Cfun, upper=1)
> >> b
> >  [1]  1.583458e-54  7.768026e-50  2.317562e-45  4.206260e-41
>  4.645737e-37
> > 3.123801e-33  1.279358e-29  3.193257e-26  4.860876e-23
> > [10]  4.516582e-20  2.564400e-17  8.908932e-15  1.896996e-12
>  2.481084e-10
> > 1.998561e-08  9.946570e-07  3.067751e-05  5.862075e-04
> > [19]  6.818952e-03  4.297061e-02  0.000000e+00  3.175122e-01
>  3.723022e-01
> > 2.364930e-01  9.144836e-02  2.190878e-02  3.252754e-03
> > [28]  2.983763e-04  1.685692e-05  5.849602e-07  1.244158e-08
>  1.619155e-10
> > 1.287603e-12  6.250149e-15  1.850281e-17  3.338241e-20
> > [37]  3.668412e-23  2.454192e-26  9.991546e-30  2.474577e-33
>  3.727226e-37
> > 3.413319e-41  1.900112e-45  6.428505e-50  1.321588e-54
> > [46]  1.650722e-59  1.252524e-64  5.772750e-70  1.615916e-75
>  2.746972e-81
> > 2.835655e-87  1.777399e-93 6.764271e-100 1.562923e-106
> > [55] 2.192373e-113 1.866955e-120 9.651205e-128 3.028623e-135
> 5.769185e-143
> > 6.670835e-151 4.682023e-159 1.994643e-167 5.157808e-176
> > [64] 8.095084e-185 7.711162e-194 4.458042e-203 1.564139e-212
> 3.330362e-222
> > 4.302974e-232 3.373500e-242 1.604721e-252 4.631224e-263
> > [73] 8.108474e-274 8.611898e-285 5.547745e-296  0.000000e+00
>  0.000000e+00
> > 0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00
> > [82]  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00
>  0.000000e+00
> > 0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00
> > [91]  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00
>  0.000000e+00
> > 0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00
> > [100]  0.000000e+00
> >
> >
> >  -thomas
> >
> >
> >
> > On Tue, Apr 9, 2013 at 3:14 PM, Janesh Devkota <janesh.devkota@gmail.com
> >wrote:
> >
> >> I am trying to solve an integral in R. However, I am getting an error
> when
> >> I am trying to solve for that integral.
> >>
> >> The equation that I am trying to solve is as follows:
> >>
> >> $$ C_m = \frac{{abs{x}}e^{2x}}{\pi^{1/2}}\int_0^t
> t^{-3/2}e^{-x^2/t-t}dt $$
> >>
> >> [image: enter image description here]
> >>
> >> The code that I am using is as follows:
> >>
> >> a <- seq(from=-10, by=0.5,length=100)
> >> ## Create a function to compute integrationCfun <- function(XX, upper){
> >>  integrand <- function(x)x^(-0.5)*exp((-XX^2/x)-x)
> >>  integrated <- integrate(integrand, lower=0, upper=upper)$value
> >>  (final <- abs(XX)*pi^(-0.5)*exp(2*XX)*integrated) }
> >>
> >>
> >> b<- sapply(a, Cfun, upper=1)
> >>
> >> The error that I am getting is as follows:
> >>
> >> Error in integrate(integrand, lower = 0, upper = upper) :
> >>  the integral is probably divergent
> >>
> >> Does this mean I cannot solve the integral ?
> >>
> >> Any possible ways to fix this problem will be highly appreciated.The
> >> question can be found on
> >>
> >>
> http://stackoverflow.com/questions/15892586/solving-an-integral-in-r-gives-error-the-integral-is-probably-divergent
> >> also.
> >>
> >> Thanks.
> >>
> >>        [[alternative HTML version deleted]]
> >>
> >> ______________________________________________
> >> R-help@r-project.org mailing list
> >> https://stat.ethz.ch/mailman/listinfo/r-help
> >> PLEASE do read the posting guide
> >> http://www.R-project.org/posting-guide.html
> >> and provide commented, minimal, self-contained, reproducible code.
> >>
> >
> >
> >
> > --
> > Thomas Lumley
> > Professor of Biostatistics
> > University of Auckland
> >
> >       [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help@r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
>
> --
> Peter Dalgaard, Professor,
> Center for Statistics, Copenhagen Business School
> Solbjerg Plads 3, 2000 Frederiksberg, Denmark
> Phone: (+45)38153501
> Email: pd.mes@cbs.dk  Priv: PDalgd@gmail.com
>
>
>
>
>
>
>
>
>


-- 
Thomas Lumley
Professor of Biostatistics
University of Auckland

	[[alternative HTML version deleted]]

