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24 changes: 12 additions & 12 deletions docs/guide/chunkgraphbvps.rst
Original file line number Diff line number Diff line change
Expand Up @@ -69,12 +69,12 @@ the following PDE:

.. math::

\begin{align*}
\begin{aligned}
(\Delta + k^2) u^{\textrm{scat}} &= 0 & \textrm{ in } \mathbb{R}^2 \setminus \Omega \; , \\
\frac{\partial u^{\textrm{scat}}}{\partial n} &= -\frac{\partial u^{\textrm{inc}}}{\partial n} & \textrm{ on } \Gamma \; , \\
\sqrt{|x|} \left( \frac{x}{|x|} \cdot \nabla u^{\textrm{scat}} - ik u^{\textrm{scat}} \right )
&\to 0 & \textrm{ as } |x|\to \infty \; ,
\end{align*}
\end{aligned}

The Green function for the Helmholtz equation is

Expand All @@ -87,10 +87,10 @@ single and double layer potential operators

.. math::

\begin{align*}
\begin{aligned}
[S_{k}\sigma](x) &:= \int_\Gamma G_k(x,y) \sigma(y) ds(y) \\
[D_{k}\sigma](x) &:= \int_\Gamma n(y)\cdot \nabla_y G_k(x,y) \sigma(y) ds(y)
\end{align*}
\end{aligned}

A robust choice for the layer potential representation for this problem is
a *right preconditioned combined field* layer potential, which is a linear combination
Expand All @@ -112,10 +112,10 @@ results in the equation

.. math::

\begin{align*}
\begin{aligned}
-\frac{\partial u^{\textrm{inc}}(x_0)}{\partial n} &= \lim_{x\in \mathbb{R}^2\setminus \Omega, x\to x_0} \beta[(S_{k} + i\alpha D_{k} S_{ik})\sigma](x) \\
&= \sigma(x_0) + \beta[S_{k}'\sigma ](x_0) + i\beta \alpha [(D_{k}' - D_{ik}')S_{ik}\sigma](x_{0}) + i \beta \alpha [S_{ik}'S_{ik}'\sigma](x_0) \;,
\end{align*}
\end{aligned}

where $S_{k}'$ and $D_{k}'$ represent the normal derivatives of
the single and double layer potentials respectively, and we have used
Expand Down Expand Up @@ -186,11 +186,11 @@ for the potential $u$ on a domain $\Omega$ with boundary $\Gamma$,
.. math::


\begin{align*}
\begin{aligned}
\Delta u &= 0 & \textrm{ in } \Omega \; , \\
u &= f_{D} & \textrm{ on } \Gamma_{D} \; , \\
\frac{\partial u}{\partial n} &= f_{N} & \textrm{ on } \Gamma_{N} \; ,
\end{align*}
\end{aligned}

where $\Gamma_{D}$ and $\Gamma_{N}$ are a partition of the boundary,
i.e. $\Gamma = \Gamma_{D} \cup \Gamma_{N}$, with
Expand Down Expand Up @@ -223,20 +223,20 @@ where

.. math::

\begin{align*}
\begin{aligned}
[S_{\Gamma_{N}}\sigma_{N}](x) = \int_{\Gamma_{N}} G_0(x,y) \sigma_{N}(y) ds(y) \; ,\\
[D_{\Gamma_{D}}\sigma_{D}](x) = \int_{\Gamma_{D}} n(y) \cdot \nabla_{y} G_0(x,y) \sigma_{D}(y) ds(y) \; .
\end{align*}
\end{aligned}

On imposing the boundary conditions, we get the following system of integral equations
for $\sigma_{D}$ and $\sigma_{N}$

.. math::

\begin{align*}
\begin{aligned}
\sigma_{D}(x) - 2[D_{\Gamma_{D}}\sigma_{D}](x) + 2[S_{\Gamma_{N}}\sigma_{N}](x) &= f_{D} \,, \,\, \textrm{ on } \Gamma_{D} \,, \\
\sigma_{N}(x) - 2[D'_{\Gamma_{D}}\sigma_{D}](x) + 2[S'_{\Gamma_{N}}\sigma_{N}](x) &= f_{N} \,,\,\, \textrm{ on } \Gamma_{N} \,,
\end{align*}
\end{aligned}

where $S'$ and $D'$ are restrictions of the normal derivatives of
$S$ and $D$ respectively.
Expand Down
24 changes: 12 additions & 12 deletions docs/guide/simplebvps.rst
Original file line number Diff line number Diff line change
Expand Up @@ -26,10 +26,10 @@ value problem

.. math::

\begin{align*}
\begin{aligned}
\mathcal{L} u &= 0 & \textrm{ in } \Omega \; ,\\
\mathcal{B} u &= f & \textrm{ on } \Gamma \; ,
\end{align*}
\end{aligned}

where :math:`\mathcal{L}` is a linear, constant coefficient PDE
operator and :math:`\mathcal{B}` is a linear trace operator that
Expand Down Expand Up @@ -87,10 +87,10 @@ Consider the Laplace Neumann boundary value problem:

.. math::

\begin{align*}
\begin{aligned}
\Delta u &= 0 & \textrm{ in } \Omega \; ,\\
\frac{\partial u}{\partial n} &= f & \textrm{ on } \Gamma \; ,
\end{align*}
\end{aligned}

where :math:`n` is the outward normal.
This is a model for the equilibrium heat distribution in a
Expand Down Expand Up @@ -133,14 +133,14 @@ results in the equation

.. math::

\begin{align*}
\begin{aligned}
f(x_0) &= \lim_{x\in \Omega, x\to x_0} n(x_0)\cdot \nabla_x
\int_\Gamma G_0(x,y) \sigma(y) \, ds(y) \\
&= \frac{1}{2} \sigma(x_0) + P.V. \int_\Gamma n(x_0) \cdot \nabla_x G_0(x_0,y)
\sigma(y) \, ds(y) \\
&=: \left [\left ( \frac{1}{2} \mathcal{I} + \mathcal{S}' \right ) \sigma
\right ] (x_0) \; ,
\end{align*}
\end{aligned}

where :math:`P.V.` indicates that the integral should be interpreted
in the principal value sense, :math:`\mathcal{I}` is the identity operator, and
Expand Down Expand Up @@ -245,12 +245,12 @@ in the exterior of the object:

.. math::

\begin{align*}
\begin{aligned}
(\Delta + k^2) u^{\textrm{scat}} &= 0 & \textrm{ in } \mathbb{R}^2 \setminus \Omega \; , \\
u^{\textrm{scat}} &= -u^{\textrm{inc}} & \textrm{ on } \Gamma \; , \\
\sqrt{|x|} \left( \frac{x}{|x|} \cdot \nabla u^{\textrm{scat}} - ik u^{\textrm{scat}} \right )
&\to 0 & \textrm{ as } |x|\to \infty \; ,
\end{align*}
\end{aligned}

The Green function for the Helmholtz equation is

Expand All @@ -263,10 +263,10 @@ single and double layer potential operators

.. math::

\begin{align*}
\begin{aligned}
[S\sigma](x) &:= \int_\Gamma G_k(x,y) \sigma(y) ds(y) \\
[D\sigma](x) &:= \int_\Gamma n(y)\cdot \nabla_y G_k(x,y) \sigma(y) ds(y)
\end{align*}
\end{aligned}

A robust choice for the layer potential representation for this problem is
a *combined field* layer potential, which is a linear combination
Expand All @@ -281,10 +281,10 @@ results in the equation

.. math::

\begin{align*}
\begin{aligned}
-u^{\textrm{inc}}(x_0) &= \lim_{x\in \mathbb{R}^2\setminus \Omega, x\to x_0} [(D-ik S)\sigma](x) \\
&= \frac{1}{2} \sigma(x_0) + [ (\mathcal{D} -ik \mathcal{S})\sigma ](x_0)
\end{align*}
\end{aligned}

where we have used the exterior jump condition for the double layer potential.
As above, the integrals in the operators restricted to the boundary must sometimes
Expand Down
16 changes: 8 additions & 8 deletions docs/guide/transmission.rst
Original file line number Diff line number Diff line change
Expand Up @@ -44,13 +44,13 @@ the following transmission boundary value problem

.. math::

\begin{align*}
\begin{aligned}
\Delta u_{j} + k_{j}^2 u_{j} &=0 & \textrm{ in } \Omega_{j} \; , j=1,2\ldots n_{r}\\
u_{r_{\ell,+}} - u_{r_{\ell,-}} &= f_{\ell} & \textrm{ on } \Gamma_{\ell} \;, \ell=1,2,\ldots n_{e}\,, \\
\beta_{r_{\ell,+}}\frac{\partial u_{r_{\ell,+}}}{\partial n} - \beta_{r_{\ell,-}}\frac{\partial u_{r_{\ell,-}}}{\partial n} &= g_{\ell} & \textrm{ on } \Gamma_{\ell}\;, \ell=1,2,\ldots n_{e}\,,\\
\sqrt{|x|} \left( \frac{x}{|x|} \cdot \nabla u_{1} - ik_{1} u_{1} \right )
&\to 0 & \textrm{ as } |x|\to \infty \;.
\end{align*}
\end{aligned}

Here $\beta_{j} = 1$ for the transverse magnetic mode and
$\beta_{j} = 1/\varepsilon_{j}$ for the transverse electric mode.
Expand All @@ -73,10 +73,10 @@ Recall that the single and and double layer potentials are given by

.. math::

\begin{align*}
\begin{aligned}
[S_{k}\sigma](x) &:= \int_\Gamma G_k(x,y) \sigma(y) ds(y)\;, \\
[D_{k}\sigma](x) &:= \int_\Gamma n(y)\cdot \nabla_y G_k(x,y) \sigma(y) ds(y) \;,
\end{align*}
\end{aligned}

where $\Gamma = \cup_{\ell=1}^{n_{e}} \Gamma_{\ell}$.

Expand All @@ -85,16 +85,16 @@ and double layer potential operators as:

.. math::

\begin{align*}
\begin{aligned}
u_{j}(x) &= \frac{1}{\beta_{j}}[D_{k_{j}}\sigma](x) - [S_{k_{j}}\mu](x) & \textrm{ in } \Omega_{j}\;,
\end{align*}
\end{aligned}

Then, imposing the boundary conditions on this representation results
in the following equation for $\sigma, \mu$:

.. math::

\begin{align*}
\begin{aligned}
\begin{bmatrix}
\sigma\\
\mu
Expand All @@ -113,7 +113,7 @@ in the following equation for $\sigma, \mu$:
\beta_{r_{\ell,+}} \beta_{r_{\ell,-}}f_{\ell}\\
g_{\ell}
\end{bmatrix} \;\; \textrm{ on } \Gamma_{\ell}\;,
\end{align*}
\end{aligned}

for $\ell=1,2,\ldots n_{e}$ where $\gamma_{\ell} = \frac{2}{\beta_{r_{\ell,+}} + \beta_{r_{\ell,-}}}$.

Expand Down
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