This section describes the elementary constructs provided for creating a matrix or vector. For each of the following functions, the parent of the result will be as follows:
Given a ring R, integers m, n >= 0 and a sequence Q, return the m x n matrix over R whose entries are those specified by Q, coerced into R. Either of m and n may be 0, in which case Q must have length 0 (and may even be null), and the m x n zero matrix over R is returned. There are several possibilities for Q:
- The sequence Q may be a sequence of length mn containing elements of a ring S, in which case the entries are given in row-major order. In this case, the function is equivalent to MatrixRing(R, n)!Q if m=n and RMatrixSpace(R, m, n)!Q otherwise.
- The sequence Q may be a sequence of tuples, each of the form <i, j, x>, where 1 <= i <= m, 1 <= j <= n, and x in S for some ring S. Such a tuple specifies that the (i, j)-th entry of the matrix is x. If an entry position is not given then its value is zero, while if an entry position is repeated then the last value overrides the previous values. This case is useful for creating sparse matrices.
- The sequence Q may be a sequence of m sequences, each of length n and having entries in a ring S, in which case the rows of the matrix are specified by the inner sequences.
- The sequence Q may be a sequence of m vectors, each of length n and having entries in a ring S, in which case the rows of the matrix are specified by the vectors.
(a) Defining a 2 x 2 matrix over Z:
> X := Matrix(IntegerRing(), 2, 2, [1,2, 3,4]); > X; [1 2] [3 4] > Parent(X); Full Matrix Algebra of degree 2 over Integer Ring
(b) Defining a 2 x 3 matrix over GF(23):
> X := Matrix(GF(23), 2, 3, [1,-2,3, 4,100,-6]); > X; [ 1 21 3] [ 4 8 17] > Parent(X); Full KMatrixSpace of 2 by 3 matrices over GF(23)
(c) Defining a sparse 5 x 10 matrix over Q:
> X := Matrix(RationalField(), 5, 10, [<1,2,23>, <3,7,11>, <5,10,-1>]); > X; [ 0 23 0 0 0 0 0 0 0 0] [ 0 0 0 0 0 0 0 0 0 0] [ 0 0 0 0 0 0 11 0 0 0] [ 0 0 0 0 0 0 0 0 0 0] [ 0 0 0 0 0 0 0 0 0 -1] > Parent(X); Full KMatrixSpace of 5 by 10 matrices over Rational Field
(c) Defining a sparse 10 x 10 matrix over GF(101):
> X := Matrix(GF(101), 10, 10, [<2*i-1, 2*j-1, i*j>: i, j in [1..5]]); > X; [ 1 0 2 0 3 0 4 0 5 0] [ 0 0 0 0 0 0 0 0 0 0] [ 2 0 4 0 6 0 8 0 10 0] [ 0 0 0 0 0 0 0 0 0 0] [ 3 0 6 0 9 0 12 0 15 0] [ 0 0 0 0 0 0 0 0 0 0] [ 4 0 8 0 12 0 16 0 20 0] [ 0 0 0 0 0 0 0 0 0 0] [ 5 0 10 0 15 0 20 0 25 0] [ 0 0 0 0 0 0 0 0 0 0] > Parent(X); Full Matrix Algebra of degree 10 over GF(101)
The following functions are "shortcut" versions of the previous general creation function, where some of the arguments are omitted since they can be inferred by Magma.
Given integers m, n >= 0 and a sequence Q of length mn containing elements of a ring R, return the m x n matrix over R whose entries are the entries of Q, in row-major order. Either of m and n may be 0, in which case Q must have length 0 and some universe R. This function is equivalent to MatrixRing(Universe(Q), n)!Q if m=n and RMatrixSpace(Universe(Q), m, n)!Q otherwise.
Given integers m and n, and a sequence Q consisting of m sequences, each of length n and having entries in a ring R, return the m x n matrix over R whose rows are given by the inner sequences of Q.
Given a sequence Q of m vectors, each of length n over a ring R, return the m x n matrix over R whose rows are the entries of Q.
Given a ring R, an integer n >= 0 and a sequence Q of length l containing elements of a ring S, such that n divides l, return the (l/n) x n matrix over R whose entries are the entries of Q, coerced into R, in row-major order. The argument n may be 0, in which case Q must have length 0 (and may even be null), in which case the 0 x 0 matrix over R is returned. This function is equivalent to MatrixRing(R, n)!Q if l=n^2 and RMatrixSpace(R, #Q div n, n)!Q otherwise.
Given an integer n >= 0 and a sequence Q of length l containing elements of a ring R, such that n divides l, return the (l/n) x n matrix over R whose entries are the entries of Q, in row-major order. The argument n may be 0, in which case Q must have length 0 and some universe R, in which case the 0 x 0 matrix over R is returned. This function is equivalent to MatrixRing(Universe(Q), n)!Q if l=n^2 and RMatrixSpace(Universe(Q), #Q div n, n)!Q otherwise.
Given a sequence Q consisting of m sequences, each of length n and having entries in a ring R, return the m x n matrix over R whose rows are given by the inner sequences of Q.
Given a sequence Q consisting of m sequences, each of length n and having entries in a ring S, return the m x n matrix over R whose rows are given by the inner sequences of Q, with the entries coerced into R.
> X := Matrix(2, [1,2, 3,4]); > X; [1 2] [3 4] > X := Matrix([[1,2], [3,4]]); > X; [1 2] [3 4]The second matrix in the previous example may be created thus:
> X := Matrix(GF(23), 3, [1,-2,3, 4,100,-6]); > X; [ 1 21 3] [ 4 8 17] > Parent(X); Full KMatrixSpace of 2 by 3 matrices over GF(23) > X := Matrix(GF(23), [[1,-2,3], [4,100,-6]]); > X; [ 1 21 3] [ 4 8 17] > X := Matrix([[GF(23)|1,-2,3], [4,100,-6]]); > X; [ 1 21 3] [ 4 8 17]
Given an integer n >= 0 and an element s of a ring R, return the n x n scalar matrix over R which has s on the diagonal and zeros elsewhere. The argument n may be 0, in which case the 0 x 0 matrix over R is returned. This function is equivalent to MatrixRing(Parent(s), n)!s.
Given a ring R, an integer n >= 0 and an element s of a ring S, return the n x n scalar matrix over R which has s, coerced into R, on the diagonal and zeros elsewhere. n may be 0, in which case in which case the 0 x 0 matrix over R is returned. This function is equivalent to MatrixRing(R, n)!s.
Given a ring R, an integer n >= 0 and a sequence Q of n ring elements, return the n x n diagonal matrix over R whose diagonal entries correspond to the entries of Q, coerced into R.
Given a ring R and a sequence Q of n ring elements, return the n x n diagonal matrix over R whose diagonal entries correspond to the entries of Q, coerced into R.
Given a sequence Q of n elements from a ring R, return the n x n diagonal matrix over R whose diagonal entries correspond to the entries of Q.
Given a matrix A of any type, return the same matrix but having as parent the appropriate matrix algebra if A is square, or the appropriate R-matrix space otherwise. This is useful, for example, if it is desired to convert a matrix group element or a square R-matrix space element to be an element of a general matrix algebra.
Given a sequence Q of length l containing elements of a ring R, such that l=((n + 1) choose 2) = n(n + 1)/2 for some integer n (so l is a triangular number), return the n x n lower-triangular matrix F over R such that the entries of Q describe the lower triangular part of F, in row major order.
Given a ring R and a sequence Q of length l containing elements of a ring S, such that l=((n + 1) choose 2) = n(n + 1)/2 for some integer n (so l is a triangular number), return the n x n lower-triangular matrix F over R such that the entries of Q, coerced into R, describe the lower triangular part of F, in row major order.
Given a sequence Q of length l containing elements of a ring R, such that l=((n + 1) choose 2) = n(n + 1)/2 for some integer n (so l is a triangular number), return the n x n upper-triangular matrix F over R such that the entries of Q describe the upper triangular part of F, in row major order.
Given a ring R and a sequence Q of length l containing elements of a ring S, such that l=((n + 1) choose 2) = n(n + 1)/2 for some integer n (so l is a triangular number), return the n x n upper-triangular matrix F over R such that the entries of Q, coerced into R, describe the upper triangular part of F, in row major order.
Given a sequence Q of length l containing elements of a ring R, such that l=((n + 1) choose 2) = n(n + 1)/2 for some integer n (so l is a triangular number), return the n x n symmetric matrix F over R such that the entries of Q describe the lower triangular part of F, in row major order. This function allows the creation of symmetric matrices without the need to specify the redundant upper triangular part.
Given a ring R and a sequence Q of length l containing elements of a ring S, such that l=((n + 1) choose 2) = n(n + 1)/2 for some integer n (so l is a triangular number), return the n x n symmetric matrix F over R such that the entries of Q, coerced into R, describe the lower triangular part of F, in row major order. This function allows the creation of symmetric matrices without the need to specify the redundant upper triangular part.
Given a sequence Q of length l containing elements of a ring R, such that l=((n) choose 2) = n(n - 1)/2 for some integer n (so l is a triangular number), return the n x n antisymmetric matrix F over R such that the entries of Q describe the proper lower triangular part of F, in row major order. The diagonal of F is zero and the proper upper triangular part of F is the negation of the proper lower triangular part of F.
Given a ring R and a sequence Q of length l containing elements of a ring S, such that l=((n) choose 2) = n(n - 1)/2 for some integer n (so l is a triangular number), return the n x n antisymmetric matrix F over R such that the entries of Q, coerced into R, describe the proper lower triangular part of F, in row major order.
(a) Defining a 3 x 3 scalar matrix over Z:
> S := ScalarMatrix(3, -4); > S; [-4 0 0] [ 0 -4 0] [ 0 0 -4] > Parent(S); Full Matrix Algebra of degree 3 over Integer Ring
(b) Defining a 3 x 3 diagonal matrix over GF(23):
> D := DiagonalMatrix(GF(23), [1, 2, -3]); > D; [ 1 0 0] [ 0 2 0] [ 0 0 20] > Parent(D); Full Matrix Algebra of degree 3 over GF(23)
(c) Defining a 3 x 3 symmetric matrix over Q:
> S := SymmetricMatrix([1, 1/2,3, 1,3,4]); > S; [ 1 1/2 1] [1/2 3 3] [ 1 3 4] > Parent(S); Full Matrix Algebra of degree 3 over Rational Field
(d) Defining n x n lower- and upper-triangular matrices for various n:
> low := func<n | LowerTriangularMatrix([i: i in [1 .. Binomial(n + 1, 2)]])>; > up := func<n | UpperTriangularMatrix([i: i in [1 .. Binomial(n + 1, 2)]])>; > sym := func<n | SymmetricMatrix([i: i in [1 .. Binomial(n + 1, 2)]])>; > low(3); [1 0 0] [2 3 0] [4 5 6] > up(3); [1 2 3] [0 4 5] [0 0 6] > sym(3); [1 2 4] [2 3 5] [4 5 6] > up(6); [ 1 2 3 4 5 6] [ 0 7 8 9 10 11] [ 0 0 12 13 14 15] [ 0 0 0 16 17 18] [ 0 0 0 0 19 20] [ 0 0 0 0 0 21]
Given an integer n and a sequence Q of length n containing elements of a ring R, return the vector of length n whose entries are the entries of Q. The integer n may be 0, in which case Q must have length 0 and some universe R. This function is equivalent to RSpace(Universe(Q), n)!Q.
Given a sequence Q of length l containing elements of a ring R, return the vector of length l whose entries are the entries of Q. The argument Q may have length 0 if it has a universe R (i.e., it may not be null). This function is equivalent to RSpace(Universe(Q), #Q)!Q.
Given a ring R, an integer n, and a sequence Q of length n containing elements of a ring S, return the vector of length n whose entries are the entries of Q, coerced into R. The integer n may be 0, in which case Q must have length 0 (and may even be null). This function is equivalent to RSpace(R, n)!Q.
Given a ring R and a sequence Q of length l containing elements of a ring S, return the vector of length l whose entries are the entries of Q, coerced into R. The argument Q may have length 0 and may be null. This function is equivalent to RSpace(R, #Q)!Q.[Next][Prev] [Right] [Left] [Up] [Index] [Root]