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## Panel Controls

###
Input Fields

The Panel for *2D Laplace Relaxation Applet* provides
three input fields in the upper left of the panel to
control the size of the calculation.
- Grid Size

The underlying grid is square and the apsect ratio of the
bounding box is determined by the number of points in the
X (horizontal) and Y (vertical) directions. These must be odd
numbers.
- User Input

Number of grid points in the X-direction.

Number of grid points in the Y-direction.

- Number of iterations

The number of iterations is addative.
Each time the *Start* button is pressed this number
of additional iterations are performed.

The geometry of the problem is controlled by
three input fields in the lower left quadrant of the panel.
- Radius

The Radius of the circle is the fraction of the horizontal
width of the bounding rectangle. This should be less than 0.5
or less than 0.5 times the ration of the height to the width,
whichever is smaller.
- X-Y coordinates of circle center.

The X-Y coordinates of circle center contol its position and
are expressed in the same units as the radius.

The boundary conditions of the problem is controlled by
two input fields in the lower left of the panel.
- Boundary Conditions

The potential on the circle and rectuangular border
are expressed in arbitrary units.

### Output Boxes

- Potential

The potential is shown in the upper right quadrant with
color coding from red at the value
set at the circle to
blue at the value at the border.
Black indicates regions where the potential is exactly the same
as the circle boundary and white indicates regions where the
potential is exactly the same as the bounding rectangle.
- Convergence

The convergence error is shown in the lower right quadrant with
error defined as the mean sqaure difference in the value of the
potential at each lattice point.

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