[R] first and second derivative calculation

[David Winsemius]

On Jan 22, 2010, at 6:49 PM, Marlin Keith Cox wrote:

> I can plot this just fine:
> t<-seq(0,4, by=.1)
> y<- t^3-6*t^2+5*t+30
> plot(t,y ,xlab="t-values", ylab="f(t)", type="l")
> This is the first derivative, how I I make a similar plot?
> t<-seq(0,4, by=.1)
> y<- t^3-6*t^2+5*t+30
> y1<-D(expression(t^3-6*t^2+5*t+30), 't')

There might be some sort of deparse() operation that one could do on  
y1, but what follows sidesteps that level of programming.


y1fn <- function(t) {3 * t^2 - 6 * (2 * t) + 5}
par(new=TRUE)
plot(t, y1fn(t), ylab="", xlab="", axes=FALSE)
  axis(side=4, at=seq(-7,5,by=1) )

> -- 
David.

> Thanks ahead of time.
>
> kc
>
>
> On Fri, Jan 22, 2010 at 12:41 PM, Doran, Harold <HDoran at air.org>  
> wrote:
>
>>> D(expression(t^3-6*t^2+5*t + 30), 't')
>> 3 * t^2 - 6 * (2 * t) + 5
>>
>>> D(D(expression(t^3-6*t^2+5*t + 30), 't'), 't')
>> 3 * (2 * t) - 6 * 2
>>
>> -----Original Message-----
>> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org 
>> ]
>> On Behalf Of Marlin Keith Cox
>> Sent: Friday, January 22, 2010 4:37 PM
>> To: r-help at r-project.org
>> Subject: [R] first and second derivative calculation
>>
>> I would like to calculate a first and second derivative and am having
>> problems finding a simple solution.  My syntax may be off as I am  
>> not a
>> mathematician, so pardon ahead of time.
>> data:
>> t<-seq(0,4, by=.1)
>> The function is:
>> H(t) = t^3-6*t^2+5*t + 30
>>
>> from here I plot the curve:
>> plot(x,y ,xlab="x-values", ylab="f(x)", type="l")
>> But would like to similarly plot the curve for both the first and  
>> second
>> derivatives.
>> I can calculate the derivatives by hand but would like to get R to  
>> do this
>> for me.
>> by hand:
>> H'(t) = 3*t^2 - 12*t + 5
>> H''(t) = 6*t-12
>> Keith
>>
>> --
>> M. Keith Cox, Ph.D.
>> Alaska NOAA Fisheries, National Marine Fisheries Service
>> Auke Bay Laboratories
>> 17109 Pt. Lena Loop Rd.
>> Juneau, AK 99801
>> Keith.Cox at noaa.gov
>> marlinkcox at gmail.com
>> U.S. (907) 789-6603
>>
>>       [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html 
>> >
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>
>
> -- 
> M. Keith Cox, Ph.D.
> Alaska NOAA Fisheries, National Marine Fisheries Service
> Auke Bay Laboratories
> 17109 Pt. Lena Loop Rd.
> Juneau, AK 99801
> Keith.Cox at noaa.gov
> marlinkcox at gmail.com
> U.S. (907) 789-6603
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

David Winsemius, MD
Heritage Laboratories
West Hartford, CT