# DiskMatrix

DiskMatrix[r]

gives a matrix whose elements are 1 in a disk-shaped region of radius r, and are otherwise 0.

DiskMatrix[r,w]

gives a w×w matrix containing a disk of 1s with radius r.

DiskMatrix[{r1,r2,},]

yields an array whose elements are 1 in an ellipsoidal region with semiaxis ri in the i index direction.

# Details and Options • The disk of 1s is always at the center of the region.
• 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[,{w1,w2,}] gives a w1×w2× array.
• DiskMatrix[{r1,,rn},w] gives a w××w array.
• DiskMatrix[All,{w1,,wn}] gives a w1××wn 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 .
• For integer r, DiskMatrix[r] yields a (2r+1)×(2r+1) matrix.

# Examples

open allclose all

## Basic Examples(1)

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

## Scope(6)

Create a square matrix:

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:

Introduced in 2008
(7.0)