Scilab Function
Last update : April 1993

fusee - a set of Scilab macro for a landing rocket problem

### Description

  FUSEE`[xdot]=fusee(t,x)` gives the dynamical motion equation for the rocket
  FINIT `finit()` Initialises the following parameters for rocket landing.
  - k: The acceleration of the rocket engines
  - gamma: The moon gravity acceleration.
  - umax: the gaz ejection flow out.
  - mcap: the mass of the space capsule.
  - cpen: penalisation in the cost function of the final state.
  FUSEEGRAD`[ukp1]=fuseegrad(niter,ukp1,pasg)` Iterate a gradient method and returns the computed control.
  - niter: number of gradient iteration steps.
  - ukp1: initial control value ( vector of sie 135 )
  - pasg: the gradient step value.
  FUSEEP`[pdot]=fuseep(t,p)` adjoint equation for the landing rocket problem.
  POUSSE`[ut]=pousse(t)` return the value of a piece wise constant control build on the discrete control `uk`
  UBANG`[uk]=ubang(tf,tcom)` returns a bang-bang control, 0 form time 0 to tcom and 1 form tcom to tf.
  FCOUT`[c,xk,pk,ukp1]=fcout(tf,uk,pasg)` optimise the following cost function by gradient iterations. `c = -m(tf) + C*( h(tf)**2 + v(tf)**2)`
  SFUSEE`[]=sfusee(tau,h0,v0,m0,Tf)` computes the rocket trajectory when a bang-bang control is used `tau` is the commutation time.
  - h0: The initial position (high)
  - v0: The initial speed ( negative if the rocket is landing )
  - m0: The total initial mass ( capsule and fuel).
  - Tf: Time horizon.
  EQUAD`[xk,pk]=equad(tf,uk)` Computes the state and adjoint state of the rocket system for a given control `ur`.
  TRAJ`[xt]=traj(t)` returns a piece wise value of the mass evolution.