       Manipulate with specified step size

• To: mathgroup at smc.vnet.net
• Subject: [mg90872] Manipulate with specified step size
• From: J Davis <texasAUtiger at gmail.com>
• Date: Sun, 27 Jul 2008 02:31:41 -0400 (EDT)

```I wanted to revisit the issue in this thread:

I have the following:

conv[f_, g_, t_] = \!\(
\*SubsuperscriptBox[\(\[Integral]\), \(0\), \(t\)]\(f[s]
g[t - s] \[DifferentialD]s\)\);

x[t_] = UnitStep[t - 2] - UnitStep[t - 3];
y[t_] = UnitStep[t - 2] - UnitStep[t - 3];

Manipulate[
Show[
Plot[{Tooltip[x[s], "f(s)"], Tooltip[y[t - s], "g(t-s)"]}, {s, 0,
8}, PlotRange -> {{-.01, 8}, {-.4, 2}},
PlotStyle -> {{GrayLevel[.85]}, {GrayLevel[.85]}},
Exclusions -> None],
Plot[Tooltip[x[s] y[t - s], "f(s)g(t-s)"], {s, t, 8.1},
PlotRange -> {{0, 8.1}, {0, 16}}, PlotStyle -> Black,
Exclusions -> None],
Plot[Evaluate[x[s] y[t - s]], {s, -.01, t}, Filling -> Axis,
PlotRange -> {{0, 8.1}, {0, 16}}, PlotStyle -> Black,
Exclusions -> None],
Plot[Evaluate[Tooltip[conv[x, y, z], "(f*g)(t)"]], {z, -.01, t},
PlotRange -> {{-.01, 8}, {0, 16}}, PlotStyle -> Blue,
Exclusions -> None],
Graphics[{Dashed, Line[{{t, -6}, {t, conv[x, y, t]}}]}],
Graphics[
Text[Style["t", Italic, Bold, Blue, 14], {t - .1, -6 + .2}]]
]
, {t, 0, 8, 1}

When I move the slider the dynamics are slow to evaluate. I would be
content to simply "play" the animation at the discrete values t=0 to
t=8 in increments of 1. However, I have been unable to obtain that
result.

Suggestions?

Thanks,
John

PS I am also surprised that these computations are slow since these
are rather simple functions involved in the convolution.

```

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