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Manipulate[
  ParametricPlot[{t, t}, {t, 0, s}],
  {s, 0, 1, 0.1}]

This code is working in Mathematica, but generates messages (ParametricPlot::plld). I tried Quiet, but result was still the same.

I looked at Off, but not understand how to use it.

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  • $\begingroup$ The reason for the message is that ParametricPlot[{0,0}] doesn't work. If you do something like Manipulate[ParametricPlot[{t, t}, {t, 0, s}], {s, 0.001, 1, 0.1}] instead (note the s initial value to 0.001) it will stop issuing the message. $\endgroup$ – Carl Lange Jan 24 at 17:31
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    $\begingroup$ The bigger question here is why does Quiet[ParametricPlot[{t, t}, {t, 0, s}]]; issue a message? $\endgroup$ – Jason B. Jan 24 at 17:38
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    $\begingroup$ I think it's because it evaluates inside the Quiet, comes back unevaluated, then reevaluates upon return. Try f /; (Print[1]; 1/0) = Null; Quiet[f]. $\endgroup$ – Chip Hurst Jan 24 at 21:26
  • $\begingroup$ Possible duplicate: mathematica.stackexchange.com/questions/120868/… $\endgroup$ – Michael E2 Jan 24 at 22:52
  • $\begingroup$ Perhaps this might be a helpful example: Manipulate[ ParametricPlot[{Sin[2 t], Cos[3 t]}, {t, 0, 2 Pi}, Mesh -> {{s}}, MeshStyle -> Red, MeshShading -> {ColorData[97][1], None}, PlotRange -> 1], {s, 0, 2 Pi}] $\endgroup$ – Michael E2 Jan 25 at 2:46
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The error message is

ParametricPlot: Endpoints for t [...] must have distinct machine-precision numerical values.

The endpoints for t are 0 and s, so when s is 0, ParametricPlot tries to plot t from 0 to 0 and produces this message.

You can solve the problem by setting the lower bound of s to a value strictly larger than 0:

Manipulate[ParametricPlot[{t,t},{t,0,s}],{s,0.1,1,0.1}]]
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