[R] integrate function

[William Dunlap]

integrate() want a vectorized function, one such that length(f(x))==length(x).
Use pmin or pmax instead of min or max.

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
> Of dan wang
> Sent: Tuesday, February 12, 2013 7:41 AM
> To: r-help at r-project.org
> Subject: [R] integrate function
> 
> Hi All,
> 
> Can any one help to explain why min and max function couldn't work in the
> integrate function directly.
> 
> For example, if issue following into R:
> 
> integrand <- function(x) {min(1-x, x^2)}
> integrate(integrand, lower = 0, upper = 1)
> 
> it will return this:
> Error in integrate(integrand, lower = 0, upper = 1) :
>   evaluation of function gave a result of wrong length
> 
> 
> However, as min(U,V) = (U+V)/2-abs(U-V)/2
> 
> Below code working;
> 
> integrand <- function(x){(1-x+x^2)/2-0.5*abs(1-x-x^2)}
> > integrate(integrand, lower = 0, upper = 1)
> 0.151639 with absolute error < 0.00011
> 
> I am confused...
> 
> 
> Dan
> 
> 	[[alternative HTML version deleted]]
> 
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