Re: Numerical calculation of derivative functions
- To: mathgroup at smc.vnet.net
- Subject: [mg17048] Re: Numerical calculation of derivative functions
- From: bawolk at ucdavis.edu (Bruce Wolk)
- Date: Wed, 14 Apr 1999 02:11:58 -0400
- Organization: University of California, Davis
- References: <7es398$cc0@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
On 12 Apr 1999 02:19:20 -0400, L B Venema <lvenema at kvi.nl> wrote: >Probably this question is very trivial, but can someone inform me >how I can force mathematica to calculate the numerical result from a >previously evaluated formal solution, like > >f[x_]:=D[sin[x],x]; >f[x]/.x->1 >Also N[%] is not more specific than D[sin[1]]. > >I think the problem is related that I cannot force Mathematica to first >evaluate the differential and subsequently substitutes the x by 1 in the >cos. (My real problem involves unknown dimensions of arrays in a non-linear >optimization problem). > >Thank you for your help, >Lars Venema Lars, I'm not sure exactly what you want, but f[x_] = D[Sin[x],x] followed by f[1]//N should work. Cheers, Bruce