Function evaluation.

  If F is a string containing the name of a function (usually

  defined by an M-file), then  FEVAL(F,x1,...,xn)  evaluates

  that function at the given arguments.  For example,

  F = 'foo',  FEVAL(F,9.64) is the same as  foo(9.64).

  FEVAL is usually used inside functions which have the names

  of other functions as arguments.