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<section id="Section-Tasks-Solver">

<title>The Solver Page</title>

<para>

The Solver Page is where it all comes together. After

<itemizedlist spacing="compact">

<listitem>

<simpara>

&materials; have been <link

linkend="Section-Tasks-Materials">assigned</link> to a

<link

linkend="Section-Tasks-Microstructure"><classname>Microstructure</classname></link>

</simpara>

</listitem>

<listitem>

<simpara>

a &skel; has been <link

linkend="Section-Tasks-Skeleton">adapted</link> to it

</simpara>

</listitem>

<listitem>

<simpara>

a &mesh; has been <link

linkend="Section-Tasks-FEMesh">created</link> from the

&skel;

</simpara>

</listitem>

<listitem>

<simpara>

<link

linkend="Section-Tasks-FieldsEquations"><classname>Fields</classname></link>

and <link

linkend="Section-Tasks-FieldsEquations"><classname>Equations</classname></link>

have been activated on the &subproblems;

</simpara>

</listitem>

<listitem>

<simpara>

and <link

linkend="Section-Tasks-BoundaryCondition">boundary

conditions</link> have been assigned,

</simpara>

</listitem>

</itemizedlist>

the Solver Page is used to find the solution to the equations.

</para>

<para>

<xref linkend="Figure-SolverPage"/> shows the layout of the Solver

Page. At the top is a Mesh Chooser for selecting the &mesh; to be

solved. The Chooser has three parts, for selecting the &mesh; and

the &skel; and &micro; in which it resides. Below the Mesh

Chooser is the <link

linkend="Section-Tasks-Solver-SolverPane">Solver Pane</link>,

where solution methods are assigned to &subproblems;, and below

that is the <link

linkend="Section-Tasks-Solver-FieldInitPane">Field Initialization

Pane</link>, where initial conditions are defined and applied. At

the bottom of the page is the <link

linkend="Section-Tasks-Solver-SolutionPane">Solution Pane</link>.

</para>

<figure id="Figure-SolverPage">

<title>The Solver Page</title>

<mediaobject>

<imageobject>

<imagedata fileref="FIGURES/gui/solver_page.png"

contentwidth="1025px" format="PNG"/>

</imageobject>

</mediaobject>

</figure>

<section id="Section-Tasks-Solver-SolverPane">

<title>The Solver Pane</title>

<para>

The Solver Pane sets the <link

linkend="Section-Concepts-Mesh-Solvers">solution

technique</link> that will be used for each &subproblem; when

the <guibutton>Solve</guibutton> button is pressed. It contains

a four column list with one row for each &subproblem; defined in

the &mesh;, and two rows of buttons that operate on the contents

of the list. Clicking on a row selects it. Double clicking on

a row is equivalent to selecting it and then pressing the <link

linkend="Section-Tasks-Solver-SolverPane-Set"><guibutton>Set

Solver</guibutton></link> button. The list comprises four

columns:

</para>

<itemizedlist>

<listitem>

<formalpara>

<title>Order</title>

<para>

When multiple &subproblems; are being <link

linkend="Section-Concepts-Mesh-Solving">solved</link>,

they are addressed sequentially in the order given by the

number in this column. The order can be changed by

selecting a &subproblem; and clicking one of the <link

linkend="Section-Tasks-Solver-SolverPane-Order"><guibutton>First</guibutton>,

<guibutton>Earlier</guibutton>,

<guibutton>Later</guibutton>, or

<guibutton>Last</guibutton></link> buttons.

</para>

</formalpara>

</listitem>

<listitem>

<anchor id="Section-Tasks-Solver-SolverPane-SolveQ"/>

<formalpara>

<title>Solve?</title>

<para>

The checkbox in this column indicates whether the

&subproblem; should be solved or not. Clicking it invokes

either the <xref

linkend="MenuItem-OOF.Subproblem.Enable_Solution"/> or

<xref linkend="MenuItem-OOF.Subproblem.Disable_Solution"/>

commands. It's a quick way of temporarily disabling a

subproblem without having to delete its solver.

</para>

</formalpara>

</listitem>

<listitem>

<formalpara>

<title>Subproblem</title>

<para>

This is just the name of the &subproblem;.

</para>

</formalpara>

</listitem>

<listitem>

<formalpara>

<title>Solver</title>

<para>

This is a short hand description of the <link

linkend="Section-Concepts-Mesh-Solvers">solver</link> that

has been assigned to the &subproblem;. If no <link

linkend="Section-Concepts-Mesh-Solvers">Solver</link> is

assigned, it will read

<userinput>&lt;none&gt;</userinput>. To see the full

details, select a line and click the <link

linkend="Section-Tasks-Solver-SolverPane-Set"><guibutton>Set</guibutton></link>

button.

</para>

</formalpara>

</listitem>

</itemizedlist>

<para>

The buttons immediately below the &subproblem; list operate on

the contents of the list. Most of them require one

&subproblem; to be selected in the list.

</para>

<itemizedlist>

<listitem>

<anchor id="Section-Tasks-Solver-SolverPane-Set"/>

<formalpara>

<title>Set</title>

<para>

Assign a solver to a &subproblem; via the <xref

linkend="MenuItem-OOF.Subproblem.Set_Solver"/> command.

The button brings up a dialog box displaying the currently

assigned solver, or the default solver if no other solver

has yet been assigned. The default is a <link

linkend="RegisteredClass-BasicStaticDriver">static</link>

solver operating in <link

linkend="RegisteredClass-BasicSolverMode">basic</link>

mode, where &oof2; makes most of the detailed parameter

choices automatically.

</para>

</formalpara>

</listitem>

<listitem>

<anchor id="Section-Tasks-Solver-SolverPane-Copy"/>

<formalpara>

<title>Copy</title>

<para>

Copy a solver from one &subproblem; to another, using the

<xref linkend="MenuItem-OOF.Subproblem.Copy_Solver"/>

command. The target &subproblem; may be in a different

&mesh;.

</para>

</formalpara>

</listitem>

<listitem>

<anchor id="Section-Tasks-Solver-SolverPane-CopyAll"/>

<formalpara>

<title>Copy All</title>

<para>

Copy all solvers from this &mesh; to another &mesh;, using

<xref linkend="MenuItem-OOF.Mesh.Copy_All_Solvers"/>.

Solvers will be copied only for those &subproblems; that

have identical names in the two &meshes;.

</para>

</formalpara>

</listitem>

<listitem>

<anchor id="Section-Tasks-Solver-SolverPane-Remove"/>

<formalpara>

<title>Remove</title>

<para>

Remove the solver from the selected &subproblem;, using

<xref linkend="MenuItem-OOF.Subproblem.Remove_Solver"/>.

The &subproblem; will not be solved until a new solver is

<link

linkend="Section-Tasks-Solver-SolverPane-Set">set</link>.

</para>

</formalpara>

</listitem>

<listitem>

<anchor id="Section-Tasks-Solver-SolverPane-RemoveAll"/>

<formalpara>

<title>Remove All</title>

<para>

Remove the solvers from all &subproblems;, making the

&mesh; unsolvable until new solvers are assigned. See

<xref linkend="MenuItem-OOF.Mesh.Remove_All_Solvers"/>.

</para>

</formalpara>

</listitem>

<listitem>

<anchor id="Section-Tasks-Solver-SolverPane-Order"/>

<formalpara>

<title>First, Earlier, Later, Last</title>

<para>

These buttons change the order of the list, by moving the

selected &subproblem; up (<guibutton>First</guibutton> or

<guibutton>Earlier</guibutton>) or down

(<guibutton>Later</guibutton> and

<guibutton>Last</guibutton>). All of the buttons invoke

the <xref linkend="MenuItem-OOF.Mesh.ReorderSubproblems"/>

command.

</para>

</formalpara>

</listitem>

</itemizedlist>

</section> <!--Solver Pane-->

<section id="Section-Tasks-Solver-FieldInitPane">

<title>The Initialization Pane</title>

<para>

The Initialization Pane is in charge of assigning <link

linkend="Section-Concepts-Mesh-InitialConditions">initial

values</link> to the &fields; and <link

linkend="RegisteredClass-FloatBC">floating boundary

conditions</link> that are defined on the &mesh;. As explained

in <xref linkend="Section-Concepts-Mesh-InitialConditions"/>,

initialization is a two step process: first an initializer is

assigned to a &field; or boundary condition, and then all the

initializers are applied.

</para>

<para>

The Initialization pane contains a list with two columns: the

names of the &fields; (or boundary conditions) and their

initializers. Items without initializers are marked with

<quote><userinput>---</userinput></quote>. Selecting an item in

the list and clicking the <guibutton>Set</guibutton> button

brings up a dialog box for setting the initializers.

Double-clicking on an item has the same effect.

</para>

<para>

When solving static problems, it's not necessary to initialize

&fields; that are <link

linkend="MenuItem-OOF.Mesh.Field.Activate">active</link>, since

values will be assigned to them by the solver. However, the

iterative solvers will converge faster if the initial values of

the &fields; are close to the actual solution. &fields; and

floating boundary conditions that are being used in time

dependent problems should always be initialized.

</para>

<para>

Note that changing a &subproblem;'s solver can affect which

items can be initialized. If the &equations; include terms,

such as <link

linkend="MenuItem-OOF.Property.Parametrize.Mechanical.MassDensity">mass

density</link> in the <link

linkend="Equation-Force_Balance">force balance</link> equation,

that contain second time derivatives, <emphasis>and</emphasis>

if the solvers are not static, then the first time derivative of

the relevant &fields; and boundary conditions must be

initialized as well. The time derivative &fields; have a

<varname>_t</varname> suffix in the list. For some reason, the

first time derivative of a boundary condition is set

differently, via an additional parameter in the

<guibutton>Set</guibutton> dialog.

</para>

<para>

In <xref linkend="Figure-SolverPage"/>,

<varname>Temperature</varname>'s initializer has been set to a

function, <userinput>x+2*y</userinput>, and the initializers for

the two components of the displacement have been set to

constants, <userinput>0.0</userinput> and

<userinput>0.01</userinput>.

</para>

<para>

The buttons below the list operate on the initializers in the

&mesh;.

</para>

<itemizedlist>

<listitem>

<formalpara>

<title>Set</title>

<para>

This button brings up a dialog box in which an initializer

can be defined for the currently selected item.

Clicking <guibutton>OK</guibutton> invokes the

<xref linkend="MenuItem-OOF.Mesh.Set_Field_Initializer"/>

or <xref

linkend="MenuItem-OOF.Mesh.Boundary_Conditions.Set_BC_Initializer"/>

command, depending on whether a &field; or a <link

linkend="RegisteredClass-FloatBC">floating boundary

condition</link> is selected in the list.

</para>

</formalpara>

</listitem>

<listitem>

<formalpara>

<title>Copy</title>

<para>

Copy all initializers from the current &mesh; (as

set in the <guilabel>Mesh Chooser</guilabel>) to another

&mesh; (selected in a dialog box), using <xref

linkend="MenuItem-OOF.Mesh.Copy_Field_Initializers"/>.

</para>

</formalpara>

</listitem>

<listitem>

<formalpara>

<title>Clear</title>

<para>

Remove the initializer from the selected item, invoking

<xref linkend="MenuItem-OOF.Mesh.Clear_Field_Initializer"/>

or <xref

linkend="MenuItem-OOF.Mesh.Boundary_Conditions.Clear_BC_Initializer"/>.

</para>

</formalpara>

</listitem>

<listitem>

<formalpara>

<title>Clear All</title>

<para>

Remove the initializers from all items, invoking <xref

linkend="MenuItem-OOF.Mesh.Clear_Field_Initializers"/>.

</para>

</formalpara>

</listitem>

<listitem>

<anchor id="Section-Tasks-Solver-ApplyInit"/>

<formalpara>

<title>Apply</title>

<para>

This button invokes <xref

linkend="MenuItem-OOF.Mesh.Apply_Field_Initializers"/> to

apply all the &field; initializers that have been defined

in the &mesh;. It does not change the &mesh;'s <link

linkend="Section-Concepts-Mesh-Time">time</link>. If the

initializers are time dependent, they are evaluated at the

&mesh;'s current time.

</para>

</formalpara>

</listitem>

<listitem>

<formalpara>

<title>Apply at Time</title>

<para>

This button invokes <xref

linkend="MenuItem-OOF.Mesh.Apply_Field_Initializers_at_Time"/>,

which sets the values of the &fields; and the &mesh;'s

<link linkend="Section-Concepts-Mesh-Time">time</link>,

which is provided by a dialog box. If any of the

initializers are time dependent, they are evaluated at the

given time.

</para>

</formalpara>

</listitem>

</itemizedlist>

</section> <!--Field Initialization Pane-->

<section id="Section-Tasks-Solver-SolutionPane">

<title>The Solution Pane</title>

<para>

The bottom part of the Solver page contains

<itemizedlist>

<listitem>

<para>

Boxes displaying the &mesh;'s current <link

linkend="Section-Concepts-Mesh-Time">time</link>, and the

desired end time of the calculation.

</para>

</listitem>

<listitem>

<para>

A box displaying a brief &mesh; status message, and a

button to request more details.

</para>

</listitem>

<listitem>

<para>

The <guilabel>Solve</guilabel> button.

</para>

</listitem>

</itemizedlist>

</para>

<para>

The current <link

linkend="Section-Concepts-Mesh-Time">time</link> cannot be

edited. It can only be changed by re-initializing the &mesh;

using the <guibutton>Apply at Time</guibutton> button, or by

solving a time-dependent problem.

</para>

<para>

The end time can be changed by typing a new value in the box.

If only static solvers are being used, the end time can be

omitted. In that case, it's assumed to be equal to the current

time.

</para>

<para>

Pressing the <guibutton>Details</guibutton> button in the

<guilabel>Status</guilabel> box displays additional status

information in the <link

linkend="Section-Windows-Messages">Message Window</link>.

</para>

<para>

The <guibutton>Solve</guibutton> button calls <xref

linkend="MenuItem-OOF.Mesh.Solve"/> to compute a solution. After

completing a time dependent solution, the end time is

automatically incremented by the length of the time evolution,

and the <guibutton>Solve</guibutton> changes to a

<guibutton>Continue</guibutton> button. This allows the

solution to be extended by simply pressing the button again.

However, if the &fields; are reinitialized or the problem

definition is changed in any way, the

<guibutton>Continue</guibutton> button reverts to being a

<guibutton>Solve</guibutton> button.

</para>

</section>

</section> <!--Solution Pane-->

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