When solving a system of differential equations numerically, I get two interpolating functions. I can graph both of these, but when I try to evaluate either of the functions at a point, it just spits out: {x1[5]} `x1[t]` is the interpolating function, and 5 is the number I chose to try to evaluate it at. I set `prsol=NDSolve[blah blah]` To evaluate it, I've tried: Evaluate[x1[5]/.prsol] and one[t_]:=x1[t]/.prsol one[5] Both of these spit out `{x1[5]}` which is contrary to what the F1 Help says it should do. A1 = .1; \[Omega]2 = \[Pi]/4; c = 10000; d = 300000; ctipmot[t_] := A1 Cos[\[Omega]2 t] prsol = NDSolve[{-c x4'[t] - k3 ((m4 g + Fpr[54/39.3701])/k3 + ctipmot[t] + x4[t]) + Fpr[x1[t] - x4[t] + 54/39.3701] + m4 g == m4 x4''[t], -c x1'[t] - d x1'[t]*Abs[x1'[t]] - Fpr[x1[t] - x4[t] + 54/39.3701] + m1 g == m1 x1''[t], x1[0] == 1, x4[0] == 0, x1'[0] == 0, x4'[0] == 0}, {x1[t], x4[t]}, {t, 0, 100}] {{x1[t] -> InterpolatingFunction[{{0.,100.}},<>][t],x4[t] -> InterpolatingFunction[{{0.,100.}},<>][t]}} (^That is the output line) Plot[Evaluate[x1[t] /. prsol], {t, 0, 32}] ^That gives me a graph Evaluate[x1[5] /. prsol] ^That gives me: {x1[5]} instead of a value.