tril - Return lower triangular part of symbolic matrix
Syntax
tril(A)
tril(A, k)
Description
tril(A) returns a triangular matrix that
retains the lower part of the matrix A. The upper
triangle of the resulting matrix is padded with zeros.
tril(A, k) returns
a matrix that retains the elements of A on and
below the k-th diagonal. The elements above
the k-th diagonal equal to zero. The values k =
0, k > 0,
and k < 0 correspond
to the main, superdiagonals, and subdiagonals, respectively.
Examples
Display the matrix retaining only the lower triangle of the
original symbolic matrix:
syms a b c
A = [a b c; 1 2 3; a + 1 b + 2 c + 3];
tril(A)
The result is:
ans =
[ a, 0, 0]
[ 1, 2, 0]
[ a + 1, b + 2, c + 3]
Display the matrix that retains the elements of the original
symbolic matrix on and below the first superdiagonal:
syms a b c
A = [a b c; 1 2 3; a + 1 b + 2 c + 3];
tril(A, 1)
The result is:
ans =
[ a, b, 0]
[ 1, 2, 3]
[ a + 1, b + 2, c + 3]
Display the matrix that retains the elements of the original
symbolic matrix on and below the first subdiagonal:
syms a b c
A = [a b c; 1 2 3; a + 1 b + 2 c + 3];
tril(A, -1)
The result is:
ans =
[ 0, 0, 0]
[ 1, 0, 0]
[ a + 1, b + 2, 0]
See Also
diag | triu
 | taylortool | | triu |  |
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