Hessian equation theory in geometric analysis revolves around fully nonlinear partial differential equations whose leading term depends on the Hessian matrix of a scalar function. These equations ...

The estimated covariance matrix of the parameter estimates is computed as the inverse Hessian matrix, and for unconstrained problems it should be positive definite. If the final parameter estimates ...

The NLP procedure provides a variety of ways for estimating parameters in nonlinear statistical models and for obtaining approximate standard errors and covariance matrices for the estimators. These ...