Movement with acceleration problems

Hello, I'm new to Unity and only took a C course about 4 years ago so I'm kinda new to this. I'm trying to make a character to move around using physics and a code ocurred to me:

using UnityEngine;

using System.Collections;

public class Movement : MonoBehaviour

{ // Use this for initialization

 Vector3 acel, vel, v0 = Vector3.zero;
 float t,x,y,z,x0,y0,z0=0, max_vel=10;
 // float mass = 1;
 void Start ()
 {
 }
 // Update is called once per frame
 void Update ()
 {
     Repositioning();
 }

 void Repositioning()
 {
     t += Time.deltaTime;
     if (Input.GetKey(KeyCode.D))
     {
         acel=Vector3.right;
     }
     if (Input.GetKey (KeyCode.A))
     {
         acel=-Vector3.right;
     }
     while (vel.magnitude < max_vel)
     {
         vel = acel*t + v0;
         v0=vel;
     }
     x = acel.x*Mathf.Pow(t,2) / 2 + x0;
     x0 = x;
     y = acel.y*Mathf.Pow(t,2) / 2 + y0;
     y0 = y;
     z = acel.z*Mathf.Pow(t,2) / 2 + z0;
     z0 = z;
     transform.Translate(x, y, z);
 }

}

My Unity editor crashes after I add this Script as a component to a Sprite and try to run it to check if it works, though the compiler tells me there are no errors. Help? Pretty Please?!