R help - Feb 2015 - integrate with vector arguments

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I'm a bit stuck.
I have to integrate a series of polynomial functions with vector
arguments.

v1<-c(1:5)
v2<-c(1:5)

f1<-function (x) {v1*x+v2*x^2}

The problem is that integrate(f1, 0, 1) does not work.
I does not, even if a pas the arguments (v1, v2)

f1<-function (x, v1, v2) {v1*x+v2*x^2}

or if i try to vectorize the function

f1<-Vectorize(function(x, v1, v2){v1*x+v2*x^2},
vectorize.args=c("v1", "v2"))

integrate(f1, 0, 1) gives an error:

Error in integrate(f1, 0, 1) :
  evaluation of function gave a result of wrong length

Any help will be greatly appreciated.

Thanks,

Marko

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Hi,

  The following works.
> f2
function(z)
{
  f1 <- function(t)
  {
    z*t + z*t^2
  }
  return(f1)
}
> sapply(1:5,function(x)integrate(f2(x),0,1)$value)
[1] 0.8333333333 1.6666666667 2.5000000000 3.3333333333 4.1666666667



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> On Feb 26, 2015, at 1:49 PM, marKo <mtoncic at ffri.hr> wrote:
> 
> v1<-c(1:5)
> v2<-c(1:5)
> 
> f1<-function (x) {v1*x+v2*x^2}
> 
> The problem is that integrate(f1, 0, 1) does not work.
> I does not, even if a pas the arguments (v1, v2)
> 
> f1<-function (x, v1, v2) {v1*x+v2*x^2}
> 
> or if i try to vectorize the function
> 
> f1<-Vectorize(function(x, v1, v2){v1*x+v2*x^2},
> vectorize.args=c("v1", "v2"))
> 
> integrate(f1, 0, 1) gives an error:
> f1<-function (X, Y) integrate( function(x) {X*x+Y*x^2}, 0, 1)$value
> fV<-Vectorize(f1)
> outer( X=v1,Y=v2, FUN= fV)
          [,1]     [,2] [,3]     [,4]     [,5]
[1,] 0.8333333 1.166667  1.5 1.833333 2.166667
[2,] 1.3333333 1.666667  2.0 2.333333 2.666667
[3,] 1.8333333 2.166667  2.5 2.833333 3.166667
[4,] 2.3333333 2.666667  3.0 3.333333 3.666667
[5,] 2.8333333 3.166667  3.5 3.833333 4.166667

? 
David Winsemius, MD
Alameda, CA, USA

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Gee. That simple. I knew that!
Thanks a lot.
Essentially, I needed only the diagonal elements.
Easily solved by:

diag(outer( X=v1,Y=v2, FUN= fV)

I am sure that there are simpler options, but that works like a charm.

Thanks a lot.

Cheers,

Marko



On 02/27/2015 06:49 AM, David Winsemius wrote:
> 
>> On Feb 26, 2015, at 1:49 PM, marKo <mtoncic at ffri.hr> wrote:
>>
>> v1<-c(1:5)
>> v2<-c(1:5)
>>
>> f1<-function (x) {v1*x+v2*x^2}
>>
>> The problem is that integrate(f1, 0, 1) does not work.
>> I does not, even if a pas the arguments (v1, v2)
>>
>> f1<-function (x, v1, v2) {v1*x+v2*x^2}
>>
>> or if i try to vectorize the function
>>
>> f1<-Vectorize(function(x, v1, v2){v1*x+v2*x^2},
>> vectorize.args=c("v1", "v2"))
>>
>> integrate(f1, 0, 1) gives an error:
> 
> 
>> f1<-function (X, Y) integrate( function(x) {X*x+Y*x^2}, 0, 1)$value
>> fV<-Vectorize(f1)
>> outer( X=v1,Y=v2, FUN= fV)
>           [,1]     [,2] [,3]     [,4]     [,5]
> [1,] 0.8333333 1.166667  1.5 1.833333 2.166667
> [2,] 1.3333333 1.666667  2.0 2.333333 2.666667
> [3,] 1.8333333 2.166667  2.5 2.833333 3.166667
> [4,] 2.3333333 2.666667  3.0 3.333333 3.666667
> [5,] 2.8333333 3.166667  3.5 3.833333 4.166667
> 
> ? 
> David Winsemius, MD
> Alameda, CA, USA
> 
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