3 I. Link der'ivatives fhrough choin role a3x1+2 十 9X190×,1 4 af 3x2 OXA+0X 9328×1a32 2 I In vecor form e)「a×2E 9X1 2 Whet we really hee ed is the inverse X1 olet]-3x, x ax. 52 l. Now we can derive the interpolation of strains