SEARCH MATHEMATICA 8 DOCUMENTATION

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DiskMatrix

DiskMatrix[r]
gives a matrix whose elements are

in a disk-shaped region of radius r, and are otherwise

DiskMatrix[r, w]
gives a w×w matrix containing a disk of

s with radius r.

DiskMatrix[{r₁, r₂, ...}, ...]
yields an array whose elements are

in an ellipsoidal region with semi-axis r_i in the i

index direction.

In DiskMatrix[r] or DiskMatrix[{r₁, ...}] the matrix or array is sized so as to just include all nonzero elements.

The disk-like region is taken to be the best discrete approximation to a circular disk possible given the size of the matrix.

DiskMatrix[All, w] gives a w×w matrix containing a disk that is as large as possible.

DiskMatrix[All, {w₁, ..., w_n}] gives a w₁×...×w_n array containing an ellipsoid that is as large as possible.

The radius r need not be an integer; in general elements are 1 if their distance from the center is not more than .

This computes and plots a square disk-shaped matrix of radius 7:

Create a rectangular ellipse-shaped matrix:

Put a disk inside a bigger matrix:

Extend the disk to the boundaries of the matrix:

Automatically choose an odd width to just fit the disk:

Extend the disk to the given width, and automatically choose the height: