Manipulate[
Animate[
Plot[
{Cos[(5/2) π (-t v0+z)] Cos[(2/15) π (-t vg+z)],Cos[(2/15) π (-t vg+z)],-Cos[(2/15) π (-t vg+z)]},
{z,-10,10},PlotRange->{-2.5,2.5},PlotStyle->{{Black},{Black,Dotted},{ Black,Dotted}},Axes->{False,True},Ticks->None,AxesStyle->Thick],
{t,0,∞},
RefreshRate->20
],
Item[Style["Grupová vs. fázová rychlost",Bold,14],Alignment->Center],
Row[{
Button["(Subscript[v, g]) < (Subscript[v, φ])",{vg=1,v0=2}],
Button["(Subscript[v, g]) = (Subscript[v, φ])",{vg=2,v0=2}],
Button["(Subscript[v, g]) > (Subscript[v, φ])",{vg=2,v0=1}],
Button["(Subscript[v, g]) < 0, (Subscript[v, φ]) > 0",{vg=-1,v0=1}],
}],
Initialization:>{vg=1,v0=2}
]