# Problem with manipulation and plot

I want to make my function trace the hypotrochoid through one period of its motion and trying to change the color of the trace, color of the radius, and change the color of the dot on it so I can view it easier

I have came up with this following function

 hypotrochoid[a_, b_, h_,t_] := {(a - b) Cos[t] + h Cos[(a - b)/b t], (a - b) Sin[t] -
h Sin[(a - b)/b t]};

myfigure[a_, b_, h_]:=Manipulate[ParametricPlot[hypotrochoid[a, b, h, t], {t, 0, c*2 \[Pi]},PlotRange -> {{-(a + b + h + 1/4), a + b + h + 1/4}, {-(a + b + h + 1/4), a + b + h + 1/4}}], {c, -1, 1}]


Though when I test it on

myfigure[5, 1, 1/2]


Nothing shows up on this testing. I know I do not have the coloring but not certain of the syntax require.

• Post complete code. Where's definition for hypotrochoid? Nov 16, 2013 at 4:57
• Posted forgot about that Nov 16, 2013 at 5:01
• It works for me. You may want to restart the kernel. Nov 16, 2013 at 5:04
• error message: ParametricPlot::prng: Value of option PlotRange -> {{-6,6},{{-6},6}} is not All, Full, Automatic, a positive machine number, or an appropriate list of range specifications. >> Nov 16, 2013 at 5:05
• Please restart your Mathematica session and try again. Nov 16, 2013 at 5:07

For coloring try:

myfigure[a_, b_, h_] := Manipulate[
ParametricPlot[
hypotrochoid[a, b, h, t], {t, 0.0000001, c*2 \[Pi]},
PlotRange -> {
{-(a + b + h + 1/4), a + b + h + 1/4},
{-(a + b + h + 1/4), a + b + h + 1/4}
},
PlotStyle -> plotColor,
Prolog -> {circleColor,
Circle[{0, 0}, a]},
Epilog -> {dotColor,
Disk[hypotrochoid[a, b, h, 2 Pi c ], .2]
}
],
{c, -1, 1},
{{plotColor, Red, "Trace"}, Red},
{{dotColor, Blue, "Dot"}, Blue},
{{circleColor, Gray, "Circle"}, Gray}
]


• very nice...if it is not intrusive, what do you use for screen capture...do you then import into mathematica and convert to animated gif or use other converter? Nov 17, 2013 at 12:57
• @ubpdqn this one. Sometimes I import them for editing (removing frames from the end or beginning, for example). Nov 17, 2013 at 13:54
• Ah very nice, I'll go play around with that syntax and try some stuff, many thanks. Nov 17, 2013 at 21:09