[R] using integrate on a function defined with if
Faheem Mitha
faheem at email.unc.edu
Sat Jun 15 08:26:10 CEST 2002
Dear R People,
I getting some curious behaviour with the integrate function. Consider the
function
foo <- function(x)
{
if(x==0)
4
else
0
}
I get the error
> integrate(foo,0,1)
Error in integrate(foo, 0, 1) : evaluation of function gave a result of
wrong length
But now consider
foo <- function(x)
{
ifelse(x==0,4,0)
}
> integrate(foo,0,1)
0 with absolute error < 0
I am guessing this may have something to do with types/classes, but I
don't see exactly what. I would be happy to be enlightened.
Yhe help page says the function must be
"f An R function taking a numeric first argument and returning a numeric
vector the same length."
But I don't see any difference in what these two return. In both cases it
is NULL.
Sincerely, Faheem Mitha.
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