$m_inverse=1  /* this could be chosen as arbitrarily small, like 0.00001 to get effectively smaller time steps) */
$v=0
$theta=0
$dt=1  /* the time interval, you can also make this of arbitrary size */
while(!$done){
    ($F_x,$F_y)=ForceCalculator($theta)  /* call your magnetics library */
    $F_perp=$F_x*sin(theta)+$F_y*cos($theta)
    $theta=$theta+$v*$dt
    $v=$v+$F_perp*$scale*dt
}