[R] question with integrate function

li li hannah.hlx at gmail.com
Tue Feb 6 19:40:20 CET 2018

Sorry. I meant in the previous email that the function h() is a monotone
decreasing function. Thanks very much.

2018-02-06 13:32 GMT-05:00 li li <hannah.hlx at gmail.com>:

> Hi all,
>   The function h below is a function of c and it should be a monotone
> increasing function since the integrand is nonnegative and integral is
> taken from c to infinity. However, as we can see from the plot, it is not
> shown to be monotone. Something wrong with the usage of integrate function?
> Thanks so much for your help.
>     Hanna
> h <- function(c){
>     g <- function(x){pnorm(x-8.8, mean=0.4, sd=0.3,
> lower.tail=TRUE)*dnorm(x, mean=9,sd=0.15)}
>     integrate(g, lower=c, upper=Inf)$value}
> xx <- seq(-20,20,by=0.001)
> y <- xx
> for (i in 1:length(xx)){y[i] <- h(xx[i])}
> plot(xx, y)

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