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Minor fixes.
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meyer-nils committed Jun 4, 2024
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4 changes: 2 additions & 2 deletions chapters/approximation_optimization.tex
Original file line number Diff line number Diff line change
Expand Up @@ -154,14 +154,14 @@ \section{Method of Moving Asymptotes}
0 &\quad \text{if} \quad \frac{\partial f}{\partial x_j} (\mathbf{x}^k) \ge 0 \\
- (x^k_j-L^k_j)^2 \frac{\partial f}{\partial x_j} (\mathbf{x}^k) &\quad \text{if} \quad \frac{\partial f}{\partial x_j} (\mathbf{x}^k) < 0.
\end{cases} \\
r_j^k &= f(\mathbf{x}^k) - \sum_j \left(\frac{p_{j}^k}{U^k_j-x^k_j} + \frac{q_{j}^k}{x^k_j-L^k_j} \right)
r(\mathbf{x}^k) &= f(\mathbf{x}^k) - \sum_j \left(\frac{p_{j}^k}{U^k_j-x^k_j} + \frac{q_{j}^k}{x^k_j-L^k_j} \right)
\label{eq:mma_end}
\end{align}
with $L^k_j < x_j < U^k_j$. The parameters $L^k_j$ and $U_j^k$ are called the lower and upper asymptotes, respectively. They can be adjusted ("move"), hence the method is termed \emph{Method of Moving Asymptotes} (MMA) \cite{Svanberg1987}. It can be proven that this is a generalization, as setting $L^k_j \rightarrow 0$ and $U^k_j \rightarrow \infty$ recovers the CONLIN method and setting $L^k_j \rightarrow -\infty$ and $U^k_j \rightarrow \infty$ recovers the SLP method.

To prevent singularities by reaching the asymptotes, we use move limits
\begin{equation}
L^k_j \le \tilde{x}_j^{-,k} \le x_j \le \tilde{x}_j^{+,k} \le U_j^k.
L^k_j < \tilde{x}_j^{-,k} \le x_j \le \tilde{x}_j^{+,k} < U_j^k.
\end{equation}
similar to SLP. These could be chosen for example as
\begin{align}
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2 changes: 1 addition & 1 deletion main.tex
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Expand Up @@ -47,7 +47,7 @@

\title{Structural Optimization}
\author{Nils Meyer}
\date{April 2024}
\date{June 2024}

\begin{document}

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