R help - Mar 2012 - gradient

Hello
In matlab we have "   gradient(F,h)   "  where h is a scalar uses h as
the
spacing between points in each direction. Now I need to use this function
in R. and I dont know how can I should define my function that I haave
"h"
in R?

thanks

	[[alternative HTML version deleted]]

Hi,

Have you looked at:

?grad

in the numDeriv package?  It works very similarly and there are examples.

Hope this helps,

Josh

On Sat, Mar 31, 2012 at 12:58 PM, mariam behboudi
<mariam.behboudi at gmail.com> wrote:
> Hello
> In matlab we have " ? gradient(F,h) ? " ?where h is a scalar uses
h as the
> spacing between points in each direction. Now I need to use this function
> in R. and I dont know how can I should define my function that I haave
"h"
> in R?
>
> thanks
>
> ? ? ? ?[[alternative HTML version deleted]]
>
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-- 
Joshua Wiley
Ph.D. Student, Health Psychology
Programmer Analyst II, Statistical Consulting Group
University of California, Los Angeles
https://joshuawiley.com/

On Mar 31, 2012, at 3:58 PM, mariam behboudi wrote:
> Hello
> In matlab we have "   gradient(F,h)   "  where h is a scalar uses
h
> as the
> spacing between points in each direction. Now I need to use this  
> function
> in R. and I dont know how can I should define my function that I  
> haave "h"
> in R?
I'm not a matlab user,  but perhaps if you define 'F' to be an n- 
column matrix and require 'h' to be of length one:

gradient <- function(F,h) { if( !is.matrix(F) | length(h) == 0 )  
{ stop() }
      return( apply(F ,2, diff)/h)  }

(The grad function in numDeriv takes a function as its first argument  
which is not what I thought you were asking for.)

-- 
David Winsemius, MD
West Hartford, CT