# [R] efficiently finding the integrals of a sequence of functions

JeffND Zuofeng.Shang.5 at nd.edu
Sun Dec 11 18:11:25 CET 2011

Thanks,Hans!

I agree that this is a good way of solving this problem.

Here is another way. Instead of defining a vector of uni-dimensional
functions and trying to integrating
each component (a uni-dimensional function), we can do something below

my.integrand<-function(x,k)
{
return(f[x,k]) ## use matrix to represent the sequence of uni-dimensional
functions
}

my.integral<-function(k) ## k=1,...,5000 denotes the function labels
{
return(integrate(my.integrand,lower=...,upper=...,k)\$value)
}

When calculating the integrals, just perform

sapply(1:5000, my.integral)

This is a way of avoiding loops but the computing time needs to be carefully
examined.

Jeff

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