Re: Calculate the first time, not each time (?)
- To: mathgroup at smc.vnet.net
- Subject: [mg94577] Re: Calculate the first time, not each time (?)
- From: Szabolcs <szhorvat at gmail.com>
- Date: Tue, 16 Dec 2008 06:04:39 -0500 (EST)
- References: <gi7ljg$cui$1@smc.vnet.net>
On Dec 16, 8:33 am, Michael Young <michaelcharlesyo... at earthlink.net>
wrote:
> Hello,
>
> I'm doing some engineering which will involve a large number of points =
> -- and I anticipate time problems if all steps are repeated for each
> one. Here's an outline of the way I'd like to approach it.
>
> shapeprimativeXvalues := N[Table[functionpX[v], {v, vlimit}]]
> shapeprimativeYvalues := N[Table[functionpY[v], {v, vlimit}]]
>
> Arriving at these will involve some calculation, and once the results
> are in, it is unnecessary that the this be repeated when the values
> are used.
>
> adaptshapetoitslocation[v_] := (various operations on or including)
> shapeprimativeXvalues[[v]] (and or) shapeprimativeYvalues[[v]]
>
> Is there a way I can instruct Mathematica to evaluate a table, (value
> or function), once, when it is first called; then not to evaluate it
> again, but to pass numerical results on request?
Use = instead of := in the assignment.
Read about the difference between Set (=) and SetDelayed (:=) in the
manual. This is an essential distinction in Mathematica.