opt.py 文件源码

def check_for_x_over_absX(numerators, denominators):
    """Convert x/abs(x) into sign(x). """
    # TODO: this function should dig/search through dimshuffles
    # This won't catch a dimshuffled absolute value
    for den in list(denominators):
        if (den.owner and den.owner.op == T.abs_ and
                den.owner.inputs[0] in numerators):
            if den.owner.inputs[0].type.dtype.startswith('complex'):
                # TODO: Make an Op that projects a complex number to
                #      have unit length but projects 0 to 0.  That
                #      would be a weird Op, but consistent with the
                #      special case below.  I heard there's some
                #      convention in Matlab that is similar to
                #      this... but not sure.
                pass
            else:
                denominators.remove(den)
                numerators.remove(den.owner.inputs[0])
                numerators.append(T.sgn(den.owner.inputs[0]))
    return numerators, denominators