This is documentation for Mathematica 7, which was
based on an earlier version of the Wolfram Language.

# CrossMatrix

 CrossMatrix[r]gives a matrix whose elements are in a centered cross-shaped region that extends r positions along each index direction, and are otherwise. CrossMatrix[r, w]gives a w×w matrix containing a cross-shaped region of s. CrossMatrix[{r1, r2, ...}, ...]yields an array whose elements are in a centered cross-shaped region that extends ri positions in the i index direction.
• The cross of 1s is always at the center of the region.
• In CrossMatrix[r] or CrossMatrix[{r1, ...}] the matrix or array is sized so as to just include all nonzero elements.
• CrossMatrix[All, w] gives a w×w matrix containing a cross shape that is as large as possible.
• CrossMatrix[..., {w1, w2, ...}] gives a w1×w2×... array.
• CrossMatrix[All, {w1, ..., wn}] gives a w1×...×wn array containing a cross-shaped region that is as large as possible.
• Elements of CrossMatrix[r] are 1 if their edit distance from the center is not more than 1.
• The parameter r need not be an integer; in an odd-dimensional array, the cross extends Floor[Abs[r+1/2]] pixels from the origin.
• The lines of the cross have width 1 if the corresponding dimension is odd and width 2 otherwise.
• For integer r, CrossMatrix[r] yields a (2r+1)×(2r+1) matrix.
This computes and plots a 3 by 3 cross matrix:
This computes and plots a 3 by 3 cross matrix:
 Out[1]=
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