[R] Adding "sum" to derivatives table

From: Martin C. Martin <martin_at_metahuman.org>
Date: Fri 05 Aug 2005 - 03:37:23 EST


Hi,

Trying this:

deriv(expression(sum(x)), "x")

Gives the error message:

        Function 'sum' is not in the derivatives table

I'd like to add it, is this difficult? If not, where is the derivatives table?

However, give how basic "sum" is, I suspect it would have been added if it were straightforward. Do functions in the derivatives table need to be vectorized? i.e. given a vector of length n, they need to produce a vector of length n? Or is there some other restriction?

Thanks,
Martin



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