What does Spdiags mean in Matlab?
example. S = spdiags( Bin , d , m , n ) creates an m -by- n sparse matrix S by taking the columns of Bin and placing them along the diagonals specified by d . example. S = spdiags( Bin , d , A ) replaces the diagonals in A specified by d with the columns of Bin .
How do you make a sparse diagonal matrix in Matlab?
Creating Sparse Matrices from Their Diagonal Elements
- S = spdiags(B,d,m,n)
- B = [ 41 11 0 52 22 0 63 33 13 74 44 24 ]; d = [-3 0 2];
- A = spdiags(B,d,7,4)
- A = (1,1) 11 (4,1) 41 (2,2) 22 (5,2) 52 (1,3) 13 (3,3) 33 (6,3) 63 (2,4) 24 (4,4) 44 (7,4) 74.
- full(A)
How do you find the diagonal of a matrix in Matlab?
D = diag( v ) returns a square diagonal matrix with vector v as the main diagonal. D = diag( v , k ) places vector v on the k th diagonal. k = 0 represents the main diagonal, k > 0 is above the main diagonal, and k < 0 is below the main diagonal.
How does sparse work in Matlab?
sparse is an attribute that you can assign to any two-dimensional MATLAB® matrix that is composed of double or logical elements. The sparse attribute allows MATLAB to: Store only the nonzero elements of the matrix, together with their indices. Reduce computation time by eliminating operations on zero elements.
Is diagonal matrix is a sparse matrix?
Tri-diagonal matrix is also another type of a sparse matrix, where elements with a non-zero value appear only on the diagonal or immediately below or above the diagonal.
How do I find the diagonal of a matrix?
A square matrix in which every element except the principal diagonal elements is zero is called a Diagonal Matrix. A square matrix D = [dij]n x n will be called a diagonal matrix if dij = 0, whenever i is not equal to j.
What is the difference between matrix and sparse matrix?
Sparse matrices are distinct from matrices with mostly non-zero values, which are referred to as dense matrices. A matrix is sparse if many of its coefficients are zero. The example has 13 zero values of the 18 elements in the matrix, giving this matrix a sparsity score of 0.722 or about 72%.
Why do we use sparse matrix?
Using sparse matrices to store data that contains a large number of zero-valued elements can both save a significant amount of memory and speed up the processing of that data. sparse is an attribute that you can assign to any two-dimensional MATLAB® matrix that is composed of double or logical elements.
How does the spdiags function in MATLAB work?
A = spdiags(B,d,m,n) creates an m-by-n sparse matrix by taking the columns of B and placing them along the diagonals specified by d. Arguments. The spdiags function deals with three matrices, in various combinations, as both input and output.
How to use spdiags to create a sparse matrix?
A = spdiags(B,d,A) replaces the diagonals specified by dwith the columns of B. The output is sparse. A = spdiags(B,d,m,n) creates an m-by-nsparse matrix by taking the columns of Band placing them along the diagonals specified by d.
When do you use Min columns in spdiags?
Diagonal elements, specified as a matrix. This matrix is typically (but not necessarily) full. spdiags uses the columns of Bin to replace specified diagonals in A. If the requested size of the output is m -by- n, then Bin must have min (m,n) columns.
How does spdiags return the same length as the main diagonal?
Because A has only four super-diagonals, spdiags returns the diagonal as all zeros of the same length as the main ( d = 0) diagonal. Examine how spdiags creates diagonals when the columns of the input matrix are longer than the diagonals they are replacing.