In addition to the two main diagonals, each diagonal that wraps around at the edges of the square, sums to the magic constant:
Squares that are pandiagonal and associative are called ultramagic. Two special classes of pandiagonal squares are:
where n is a doubly even order. See note.
Squares that are compact and complete are called most-perfect.
PandiagonalSquares makes these squares using the methods outlined below. MagicSquaresSODLS also makes pandiagonal and ultramagic squares for some orders.
Order5Special makes the 3600 order 5 pandiagonal magic squares.
Margossian's "cavalière" method. See under "Types de carrés à ordonnance cavalière" and "Carrés magiques impairs de modules composés" in Margossian. This method is for all odd orders n > 3. Some of the squares are ultramagic. Some, for orders that are a multiple of 3, are compact_{n/3}.
Cavalier Note: Margossian describes the path of successive group numbers as similar to knight moves in the game of chess. In making these squares, the horizontal and vertical steps are not limited to the 1 and 2 cells of the knight move. They may be any appropriate lengths in the range 1-n to n-1, (with wrap-around).
A method, also attributed to Margossian, given in Rouse Ball. See under "SYMMETRICAL AND PANDIAGONAL SQUARES", page 208. This method is for odd orders n > 3, that are a multiple of 3.
These are all compact_{n/3}. Some are ultramagic.
The Siamese method. See "Demanding the square is panmagic" in math behind the Siamese method. This method is for odd orders n > 3, that are not a multiple of 3. Some of the squares are ultramagic.
In THE ZEN OF MAGIC SQUARES, CIRCLES, AND STARS, page 255, Clifford Pickover says "Until the 1990s, everyone believed that it was impossible to construct a regular pandiagonal order-9 magic square...".
Actually, these squares were known long before the 1990s. For example, below is one from 1908 and another from 1878.
This is the first of seven given in A.Margossian, DE L'ORDONNANCE DES NOMBRE DANS LES CARRÉS MAGIQUES IMPAIRS, 1908, .txt:
And, this one is given in A.H.Frost, ON THE GENERAL PROPERTIES OF NASIK SQUARES, 1878, .txt:
Note: 72 at row 3, column 6 is corrected to 69.
This order 15 appears in the same article, .txt:
There are no pandiagonal magic squares of singly-even order.
This was shown by A.H. Frost (1878) and C. Planck (1919). See
references.
There are singly-even magic squares in which only four diagonals do not sum to
the
magic constant.
This is the minimum because:
PandiagonalSquares makes these squares using a process involving three main steps:
where, for example, L' is the symmetric complement of L.
Possible patterns for n = 6, 10, 14, 18 are:
Orders 6, 14, 22, 30, ... and 10, 18, 26, 34, ... have similar patterns, (differences shown in blue).
Move 1 or more row(s) and/or column(s) from one side to the opposite side to make the square magic.
Methods I, II, and III squares are converted to pandiagonal by Planck's A-D method.
Al_Asfizari associative Method I.
Al_Asfizari associative Method II.
C. Planck associative Method III.
A method, attributed to Margossian, given in Rouse Ball. See under "SYMMETRICAL AND PANDIAGONAL SQUARES", page 208.
These squares are all most-perfect. Some are bent diagonal. Except for order 4, they are U zigzag_{n/4}.
Margossian's "cavalière" method. See under "Types de carrés à ordonnance cavalière" and "Note II. - Sur la transformation des groupes naturels de module composé. Application aux modules pairs" in Margossian. See note.
These squares have various levels of compactness, U and V zigzag. Some are complete and some are most-perfect.
There are 48 order 4 pandiagonal magic squares. These are TYPE I in the classification by Dudeney. They are all most-perfect.
A pandiagonal magic square remains pandiagonally magic if a row or column is moved from one side of the square to the opposite side. So, each order n square makes a total of n^{2} squares in this way. A near-pandiagonal magic square can be transformed into (n-2)^{2} near-pandiagonal magic squares in this way, (and 4(n - 1) semi-magic squares).
In addition to the two main diagonals, all the diagonals, (parallel to only 1 main diagonal), that wrap around at the edges of the square, each add up to the magic constant:
There are 77580 order 5 pandiagonal 1-way magic squares.
Here are order 7 and order 9 pandiagonal 1-way magic squares.
There are no pandiagonal 1-way magic squares of singly-even order. See Planck's proof.
For doubly-even orders greater than 4, there are pandiagonal 1-way magic squares. Here are order 8, order 12 examples.
There are squares in which all diagonals have the magic sum but the rows and columns may not. One example of these is made by simply writing the ordered sequence 1 to n^{2}:
These are called natural squares. See Planck. See also reversible squares.
Ball, W.W.Rouse and H.S.M. Coxeter "MATHEMATICAL RECREATIONS AND ESSAYS,
Eleventh Edition"
https://epdf.pub/queue/mathematical-recreations-and-essays-11th-rev-ed.html, page 208
Candy, Albert L. "Pandiagonal Magic Squares of Prime Order"
http://babel.hathitrust.org/cgi/pt?id=uc1.b4250447;view=1up;seq=7
Candy, Albert L. "Pandiagonal Magic Squares of Composite Order"
http://babel.hathitrust.org/cgi/pt?id=mdp.39015010791260;view=1up;seq=5
Danielsson, Holger "Magic Squares" https://www.magic-squares.info/en.html
Dudeney, Henry E. "Magic Square Problems"
https://archive.org/details/AmusementsInMathematicspdf
Frost, A.H. "ON THE GENERAL PROPERTIES OF NASIK SQUARES"
http://books.google.com/books?id=qxMLAAAAYAAJ&pg=PA34#v=onepage&q&f=false
Heinz, Harvey "Order 4 Magic Squares, Group I ...The pandiagonals"
www.magic-squares.net/order4list.htm#Group I
Heinz, Harvey "Ultra Magic squares - Walter Trump" http://www.magic-squares.net/trump-ultra.htm
Hospel, Ton "The math behind the Siamese method of generating magic squares"
http://www.xs4all.nl/~thospel/siamese.html
Margossian, A. "DE L'ORDONNANCE DES NOMBRE DANS LES CARRÉS MAGIQUES IMPAIRS"
https://archive.org/details/delordonnancede00marggoog
Pickover, Clifford A. "THE ZEN OF MAGIC SQUARES, CIRCLES, AND STARS"
https://epdf.pub/the-zen-of-magic-squares-circles-and-stars-an-exhibition-of-surprising-structure.html
Planck, C. "PANDIAGONAL MAGICS OF ORDERS 6 AND 10 WITH MINIMAL NUMBERS."
http://www.jstor.org/stable/27900742?seq=1#page_scan_tab_contents
Weisstein, Eric W. "Panmagic Square." From MathWorld--A Wolfram Web Resource.
http://mathworld.wolfram.com/PanmagicSquare.html