Re: Problem in Evaluate/Manipulate
- To: mathgroup at smc.vnet.net
- Subject: [mg88657] Re: Problem in Evaluate/Manipulate
- From: Szabolcs Horvát <szhorvat at gmail.com>
- Date: Sun, 11 May 2008 15:16:25 -0400 (EDT)
- Organization: University of Bergen
- References: <g03v2l$bno$1@smc.vnet.net>
wiso wrote:
> I have a problem with this code:
>
> Solution =DSolve[{x^\[Prime][t]==a x[t]+b y[t],y^\[Prime][t]==c x[t]+d
> y[t],x[0]==x0,y[0]==-10},{x[t],y[t]},t];
>
> Manipulate[
> Solutions = Evaluate [Table[{x[t],y[t]}/.Solution[[1]],
> {x0,-10,10,10}]]
> ,{a,-1,1},{b,-1,1},{c,-1,1},{d,-1,1}]
>
> I want to solve only one time the PDE, then I placed it outside the
> Manipulate. The code doesn't evaluate the solution with the dynamic
> values.
>
Remove "Solutions =". From the doc page of Evaluate:
"Evaluate only overrides HoldFirst, etc. attributes when it appears
directly as the head of the function argument that would otherwise be held."
This will work:
Manipulate[
Evaluate[Solutions =
Table[{x[t], y[t]} /. Solution[[1]], {x0, -10, 10, 10}]], {a, -1,
1}, {b, -1, 1}, {c, -1, 1}, {d, -1, 1}]