[R] question with integrate function

li li hannah.hlx at gmail.com
Tue Feb 6 19:32:33 CET 2018

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.

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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