Function shapeFunctionsNaturalDerivatives

SRC/element/shell/ASDShellQ4.cpp:188–199

shape function derivatives in iso-parametric space

    // shape function derivatives in iso-parametric space
    inline void shapeFunctionsNaturalDerivatives(double xi, double eta, Matrix& dN)
    {
        dN(0, 0) = -(1.0 - eta) * 0.25;
        dN(1, 0) = (1.0 - eta) * 0.25;
        dN(2, 0) = (1.0 + eta) * 0.25;
        dN(3, 0) = -(1.0 + eta) * 0.25;

        dN(0, 1) = -(1.0 - xi) * 0.25;
        dN(1, 1) = -(1.0 + xi) * 0.25;
        dN(2, 1) = (1.0 + xi) * 0.25;
        dN(3, 1) = (1.0 - xi) * 0.25;
    }

    /** \brief JacobianOperator
     *