Eine Welle

1. Definitionen und Plot 3D

rem; ove;   Remove["Global`*"]

ω = 2;  k = 3;  yA = 2.8;
y[t_, x_] := 
        yA  Cos[ω t  +  k x];
Plot3D[y[t, x], {t, 0, 8}, {x, 0, 8}, 
        PlotPoints -> 80];

2. Tabellen und Plotserie mit änderndem Ortsintervall

Plot[y[t, 1], {t, 0, 8}, PlotPoints -> 80];

Plot[y[1, x], {x, 0, 8}, PlotPoints -> 80];

Table[
        Plot3D[y[t, x], {t, 0, 8}, {x, 0 + k, 4 + k}, 
          PlotPoints -> 80], {k, 0.5, 20, 1}];

Remove["Global`*"]

2. Geplotete Punkte (Listen)

T = 2  Pi;  λ = 2  Pi;  c = 100;
ω = 2 Pi/(T);  k = 2  Pi/( λ);  
    yA = 1;
y[t_, x_] := yA  Cos[ω t  -  k x]; Δt = 
      2  Pi/c; Δx = 2  Pi/c;
y[u Δt,  s Δx]

tab[u_] := 
        Table[y[u Δt,  s Δx], {s, 0, c}] // 
          N;

Table[tab[u], {u, 0, c}]

Table[
      ListPlot[tab[u], PlotStyle -> PointSize[0.015]], {u, 0, 
        c}]