# Questions tagged [constraints]

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### How much better a bounded BFGS is compared to augmented Lagrangian method with BFGS?

I mean, in handling boxed constraints? In terms of stability, and more importantly, the numerical performance? I have already written some well-optimized and well-tested C/CUDA/C++ codes for ...
72 views

### Hanging nodes in deal.ii tutorials: how is the continuity constraint imposed?

While looking at step6 of deal.ii tutorials, I decided to try to understand how the constraints coming from hanging nodes are imposed. So I started by watching video lecture 16 by prof. Bangerth As ...
30 views

### Differences in using Clausius-Duhem inequality vs Principle of Virtual Work/Power in derriving constitutive equations?

I am a novice getting my toes wet in continuum mechanics and nonlinear elasticity. I have seen papers that use both approaches in developing constitutive connections to compliment balance equations of ...
371 views

### What is the mathematical and physical principle behind of RBE2 element？

I am writing a 3d linear finite element code to solve the standard linear elasticity equation on a tetrahedron mesh of a gearbox. Notice that, the two rectangular plates above the gearbox are fixed, ...
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The perspective of a function $f : \mathbb{R}^n \to \mathbb{R}$ is the function $g: \mathbb{R}^n \times \mathbb{R} \to \mathbb{R}$ where $g$ is defined as $$g(x,t) = tf(x/t)$$ with $$\mathbf{\text{dom}... 0answers 81 views ### About Convex Geometry A consistency notion in constraint programming: Let P = (X, D, C) be a CSP. Given a set of variables Y \subseteq X with |Y| = k -1, a locally consistent instantiation I on Y is k-... 0answers 242 views ### the augmented global stiffness matrix is not positive semi-definite using Lagrange Multipliers method within FEM The augmented global stiffness matrix is not positive semi-definite when using Lagrange Multipliers method to enforce boundary constraints on a simple square domain of integral form: I am considering ... 0answers 188 views ### Maxwellian distribution of velocities with Shake algorithm present I am writing a code to perform hybrid monte carlo molecular dynamics. To do this, I need to have a code to initialize the velocities of all particles according to a maxwell distribution. The code is ... 0answers 51 views ### Numerical Implementation of "integrates to some values" type constraint in convex solvers? I am maximizing a linear functional subject to an integrates to one constraint. More explicitly, my problem is$$\begin{align} &\max_{x \in \mathbb{R}^n}\quad c \cdot x\\ &\text{subject to} \...
I have a diffusion problem which can be broken down to be: $-\Delta u = f(u)$ on $\Omega ~/~ \Omega_{int}$ $u = 1$ on $\Omega_{int}$ Note that this is an internal Dirichlet constraint to the ...
I am implementing an optimization problem using semi-definite approach. One of my constraints is of following form $trace(A∗X)−(k∗trace(A∗X))+(k∗\sqrt {(trace(B∗X)} )==0$ where k is a constant, A ...