Under what conditions $J^{T}J$ equals to the Hessian?
9905
Why is the approximation of Hessian$= J^TJ$ reasonable?
115712
Application of Derivatives rigorous proof
45071
Having the derivative be an operator
100810
Let $V$ be spherically symmetric and $W$ i.i.d. Gaussian. Then $E[V|V+W=t]=g(\|t\|)$
95774
$\frac{\partial^2 u}{\partial t^2}-c^2\frac{\partial^2u}{\partial x^2}=0\text{ implies } \frac{\partial^2 u}{\partial z \partial y}=0$
53640
Equality of mixed partial derivatives
153406
$[F(t):F(t^n)]=n$ where $t$ is trascendental
104258
Proof Verification: $\dim\mathrm{Im} T+\dim\ker T=\dim V$
8844
Higher-order partial derivatives w.r.t. variable raised to some power
53767
How to prove that derivatives have the Intermediate Value Property
114172
Derivation of Hamilton-Jacobi theory using canonical transformations
96022
Symmetry of second derivative - Sufficiency of twice-differentiability
77891
$(U\circ T)^{*} = T^{*}\circ U^{*}$
142892
Lagrangian Mechanics - Commutativity Rule $\frac{d}{dt}\delta q=\delta \frac{dq}{dt} $
45363
Show that both mixed partial derivatives exist at the origin but are not equal
75548
second derivative of the inverse function
14656
The differential equation $xu_{x}+yu_{y}=2u$ satisfying the initial condition $y=xg(x),u=f(x)$