utilities.py 文件源码

def smooth_abs(x, dx=0.01):
    """smoothed version of absolute vaue function, with quadratic instead of sharp bottom.
    Derivative w.r.t. variable of interest.  Width of quadratic can be controlled"""

    x, n = _checkIfFloat(x)

    y = np.abs(x)
    idx = np.logical_and(x > -dx, x < dx)
    y[idx] = x[idx]**2/(2.0*dx) + dx/2.0

    # gradient
    dydx = np.ones_like(x)
    dydx[x <= -dx] = -1.0
    dydx[idx] = x[idx]/dx


    if n == 1:
        y = y[0]
        dydx = dydx[0]

    return y, dydx