How is calculation of initial tangen (Gmax/G0) and strain relationship?

[M Hamzah Fansuri]

Hi everyone

I am a researcher where the focus on soil dynamics. I need your contribution to give me more information.
I already calculated shear stress and strain curve. But, I want to know the calculation of typical shear modulus and strain response. If I calculate in the traditional way, may need more time and I think it difficult. In this special occasions, I would like to ask what is software can provide this feature? Does anyone think that?
Attached picture what I get data so far. Fig. a (I already have), Fig. b (the result what I need).

Fig. a

Fig. b

Thank you for your assistance

Best regards,
Hamzah