### 1.15 Linesearch, minimize a function along dx ¶

#### Helptext: ¶

    [a,fx,nev] = line_min (f, dx, args, narg, h, nev_max) - Minimize f() along dx

    INPUT ----------
    f    : string  : Name of minimized function
    dx   : matrix  : Direction along which f() is minimized
    args : cell    : Arguments of f
    narg : integer : Position of minimized variable in args.  Default=1
    h    : scalar  : Step size to use for centered finite difference
    approximation of first and second derivatives. Default=1E-3.
    nev_max : integer : Maximum number of function evaluations.  Default=30

    OUTPUT ---------
    a    : scalar  : Value for which f(x+a*dx) is a minimum (*)
    fx   : scalar  : Value of f(x+a*dx) at minimum (*)
    nev  : integer : Number of function evaluations

    (*) The notation f(x+a*dx) assumes that args == {x}.

    Reference: David G Luenberger's Linear and Nonlinear Programming