Dear all,
many thanks, great work. Here is the feature which Peter suggested (it also
includes a string containing the variable name):
DD - function(f, var.string=x, order=1){
res - f
body.res - body(f)
i - 1
while(i = order){
body.res -
Okay, great. Thanks.
Cheers,
Marius
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R-help@r-project.org
On Jul 29, 2010, at 11:27 PM, Wu Gong wrote:
## specify the function string
f.str - x^alpha
## higher derivatives
DD - function(f.str, x = 2, alpha=3,order = 1){
expr.s - parse(text=f.str)
while(order=1) {
expr.s - D(expr.s,x)
order - order-1}
eval(expr.s)
}
compute
-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
Behalf Of peter dalgaard
Sent: Friday, July 30, 2010 9:52 AM
To: Wu Gong
Cc: r-help@r-project.org
Subject: Re: [R] how to get higher derivatives with deriv
On Jul 29, 2010, at 11:27 PM, Wu Gong wrote:
## specify the function
On Jul 30, 2010, at 4:28 PM, Ravi Varadhan wrote:
I am not as lazy as Peter (but neither am I as good as him)! So, please
allow me to take a stab at completing his exercise:
Deriv - function(fn, order=1) {
ddf - fn
body(ddf) - D(body(f),x)
### Typo: body(ddf) or body(fn)
if (order 1)
Hi Peter,
Here is my homework :)
DD - function(f,order=1){
f.str - body(f)
while(order=1) {
f.str - paste('D(',f.str,',x)',sep=)
order - order-1}
ddf - f
body(ddf) - eval(parse(text=f.str))
ddf}
f - function(x,alpha) x^alpha
DD(f)(2,3)
g
Dear ExpeRts,
I have trouble implementing a function which computes the k-th derivative of a
specified function f and returns it as a function. I tried to adapt what I
found under ?deriv but could not get it to work. Here is how it should look
like:
## specify the function
f - function
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