
  The biomechanical acquisition handle H is represented as a double and can
  be only used with the btk* functions.

  [FORCEPLATES FORCEPLATESINFO] = BTKGETFORCEPLATFORMS(H) returns 
  force platform's channel' informations in FORCEPLATESINFO.  The structure 
  FORCEPLATESINFO has the following fields:
    - FORCEPLATESINFO(i).FREQUENCY
    - FORCEPLATESINFO(i).UNITS
    - FORCEPLATESINFO(i).CAL_MATRIX
  Field FREQUENCY contains the force platform's channel' frequency.  
  Field UNITS contains the unit of