solDiff[l_, phi0_, dphi0_, tmax_, dt_] := Module[{phi = phi0, dphi = dphi0, ddphi = 0, finalList, list = ConstantArray[0, Floor[tmax/dt] + 1], t0, tFall = -1},
  finalList = Transpose[{list, list, list, list}];

  For[t0 = 0, t0 <= tmax, t0 += dt,

   finalList[[t0/dt + 1, 4]] = ddphi;
   finalList[[t0/dt + 1, 3]] = dphi;
   finalList[[t0/dt + 1, 2]] = phi;
   finalList[[t0/dt + 1, 1]] = t0;

   If[phi >= Pi/2,
    If[tFall == -1, tFall = t0];
    phi = Pi/2; dphi = 0;ddphi = 0;,

    ddphi = Sin[phi]/((2*l)/(3*9.81));
    dphi += dt*ddphi;
    phi += dt*dphi;]
   ];
  {finalList, tFall}
  ]

solphi[l_, phi0_, dphi0_, tmax_, dt_] := Transpose[{solDiff[l, phi0, dphi0, tmax, dt][[1, All, 1]], solDiff[l, phi0, dphi0, tmax, dt][[1, All, 2]]}]

soldphi[l_, phi0_, dphi0_, tmax_, dt_] := Transpose[{solDiff[l, phi0, dphi0, tmax, dt][[1, All, 1]], solDiff[l, phi0, dphi0, tmax, dt][[1, All, 3]]}]

solddphi[l_, phi0_, dphi0_, tmax_, dt_] := Transpose[{solDiff[l, phi0, dphi0, tmax, dt][[1, All, 1]], solDiff[l, phi0, dphi0, tmax, dt][[1, All, 4]]}]