# Tangent matrix terms in Abaqus UEL

I have problems in the calculation of the tangent matrix terms in an Abaqus UEL subroutines, do you have suggestion on how to take tensor derivatives? For example: $$\frac{d\underline{\underline{T}}}{d\underline{\underline{F}}}=\frac{d}{d\underline{\underline{F}}} \left( a\underline{\underline{F}}^{-T}\right)$$ where $$a$$ is a constant.

Thank you.