[R] How to provide a result from D(f(x), "x") to a curve(f'(x)) ???

[David Winsemius]

On Feb 17, 2010, at 1:48 PM, Gabor Grothendieck wrote:

> Try this:
>
> do.call(curve, list(D(expression(x^3), "x")))

This also worked, after noting that str() told me the D() object had a  
"language" attribute, but given that it was not the chosen method by  
Gabor, it may have some deficiency about which I am unaware:

curve( eval(D(expression(x^3), "x") ) )

His do.call method does result in a more intuitive labeling of the y- 
axis.

-- 
David.
>
> On Wed, Feb 17, 2010 at 1:31 PM, Walmes Marques Zeviani
> <walmeszeviani at hotmail.com> wrote:
>>
>> Hi all,
>>
>> I want to provide the result from D() to curve(), because I want to  
>> plot the k-th derivative of some functions. Actually, I copy from  
>> console the result given by D() and paste inside curve(). With a  
>> lot of functions and high degree differentiation this process is  
>> tedious. Can I provide directly??
>>
>> # what I actually have done (very simple function)
>> D(expression(x^3), "x") # copy this result
>> curve(3 * x^2) # paste inside
>>
>> # my failed attempts
>> curve(as.expression(D(expression(x^3), "x")))
>> curve(as.character(as.expression(D(expression(x^3), "x"))))
>> curve(noquote(as.character(as.expression(D(expression(x^3), "x")))))
>>
>> Thanks in advance.
>> Walmes Zeviani, Brasil.
>> ________________________________________________________________

>

David Winsemius, MD
Heritage Laboratories
West Hartford, CT