Manipulate, Opacity, slow down

[janos]

I wonder if you can give me some hints without a code.
I have a program using Manipulate[ParametricPlot[f[a]]].
1. If I define outside the function f used in ParametricPlot, and then
insert the function name into ParametricPlot, then the program slows
down extremely compared to the version when the formula of the
function is inserted.
2. If I add Opacity to the Directives, again the timing increases
tremendously.

If you think you could help seeing the (long) code I'll be ready to
show it.

Thank you,

J=E1nos

[Jens-Peer Kuska]

Hi,

adding transparency will slow down an any hardware accelerated
rendering system.

And with
f1[t_] := {Cos[t], Sin[t], t}

AbsoluteTiming[
ParametricPlot3D[f1[t], {t, 0, 2 Pi}, PlotPoints -> 4096]][[1]]

gives
0.1110000

but
AbsoluteTiming[
ParametricPlot3D[f1[t] // Evaluate, {t, 0, 2 Pi},
PlotPoints -> 4096]][[1]]

gives
0.075

and this is nearly the same as

AbsoluteTiming[
ParametricPlot3D[{Cos[t], Sin[t], t}, {t, 0, 2 Pi},
PlotPoints -> 4096]][[1]]

with
0.079

Regards
Jens

[Sjoerd C. de Vries]

Janos,

I don't see much difference between

Manipulate[
ParametricPlot[{Sin[a u], Cos[ u/a]}, {u, 0, 4 Pi}], {a, 1, 5}]

and

f[a_] := ParametricPlot[{Sin[a u], Cos[ u/a]}, {u, 0, 4 Pi}]
Manipulate[f[a], {a, 1, 5}]

What is it precisely you did?

Cheers -- Sjoerd

[Alexei Boulbitch]

Hi, Janos,

Without the code it is not quite clear, why the 2D parametric plot is
noticeably slowed down in your case. I met such situations only in 3D
cases. Probably your function is too heavy for whatever reason.
Anyway, if you need the result for a presentation (for what else?), you
may be quite sutisfied with timing of the discrete Manipulate version,
instead of the continuous one, like the following:

f[a_] := ParametricPlot[{Sin[a u], Cos[u/a]}, {u, 0, 4 Pi}]

Manipulate[f[a], {a, 1, 5, 0.5}]

If this is still too slow in your case, try the FlipView like below:

tab = Table[
ParametricPlot[{Sin[a u], Cos[u/a]}, {u, 0, 4 Pi}], {a, 1, 5, 0.5}];
FlipView[tab]

This must be fast.

Alexei

n May 12, 11:43 am, janos <janostothmeis... at gmail.com> wrote:
> I wonder if you can give me some hints without a code.
> I have a program using Manipulate[ParametricPlot[f[a]]].
> 1. If I define outside the function f used in ParametricPlot, and then
> insert the function name into ParametricPlot, then the program slows
> down extremely compared to the version when the formula of the
> function is inserted.
> 2. If I add Opacity to the Directives, again the timing increases
> tremendously.
>
> If you think you could help seeing the (long) code I'll be ready to
> show it.
>
> Thank you,
>
> J=E1nos

--
Alexei Boulbitch, Dr., habil.
Senior Scientist

IEE S.A.
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Luxembourg

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