Thank you very much for your reply!
It is not an assignment.
What I want to do is what we often do. If we have a bivariate function of x
and p,
I first fix x and integrate out p. Then the resultant function is only in
terms of x.
Here f1 is a bivariate function of x and p.
> f1 <- function (p,x)
+ {
+ prod(p*x+(1-p)*x^{2})
}
f2 is a function of x only after integrating out p from f1. Here f1 is the
integrand, x is the additional argument to be
passed to f1. The integration is in terms of p.
> f2 <- function(x)
+ {
+ integrate(f1, lower=0,upper=1, x)
+ }
There is error output when I evaluate f2 at specific x values. See below:
> f2(c(2,3))
Error in integrate(f1, lower = 0, upper = 1, x) :
evaluation of function gave a result of wrong length
In addition: Warning messages:
1: In p * x :
longer object length is not a multiple of shorter object length
2: In (1 - p) * x^{ :
longer object length is not a multiple of shorter object length
Can any one give me some suggestions! Thank you!
2009/12/5 David Winsemius <dwinsem...@comcast.net>
>
> On Dec 5, 2009, at 4:59 PM, li li wrote:
>
> Hello,
>> I have some trouble in terms of using integrate function in R.
>>
>> f1 is a function of p and x where x is supposed to be a vector. (See the
>> code).
>> Then I want to write function f2 which is a function of the vector
>> x after I integrate out p.
>> Can some one give me some help? Many thanks!
>> Hannah
>>
>> f1 <- function (p,x)
>>>
>> + {
>> + y <- p*x+(1-p)*x^{2}
>> + prod(y)
>> + }
>>
>>>
>>> f2 <- function(x)
>>>
>> + {
>> + integrate(f1, 0,1, x)
>>
>
> Just looking at the help page for integrate makes me wonder what you are
> doing. There are 3 named arguments before the dots, so 0 and 1 will become
> "lower" and "upper", while x is not among the named arguemnts, so I suppose
> x will go to f1 as "p". But f1 takes two arguments, so where will it get the
> second argument? Maybe if you would tell us a bit more about why you made
> those functions the way you did, it would help. I am guessing it's classwork
> but perhaps not.
>
>
> + }
>>
>> f2(x=c(1,2))
>>>
>> Error in integrate(f1, 0, 1, x) :
>> evaluation of function gave a result of wrong length
>> In addition: Warning messages:
>> 1: In p * x :
>> longer object length is not a multiple of shorter object length
>> 2: In (1 - p) * x^{ :
>> longer object length is not a multiple of shorter object length
>>
>> [[alternative HTML version deleted]]
>>
>
> --
>
> David Winsemius, MD
> Heritage Laboratories
> West Hartford, CT
>
>
[[alternative HTML version deleted]]
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