1. A method of estimating a nonlinearity profile of a material, the method comprising: (a) providing a magnitude of a transform of a measured nonlinearity profile measured from the material; (b) providing an estimated phase term of the transform of the measured nonlinearity profile; (c) multiplying the magnitude and the estimated phase term to generate an estimated transform; (d) calculating an inverse transform of the estimated transform; and (e) calculating a real component of the inverse transform to generate an estimated nonlinearity profile.