issparse — Test whether a value is stored as a sparse matrix.
tf = issparse(A) returns true when A is a RunMat sparse matrix and false for dense arrays, scalars, containers, objects, strings, and gpuArray handles.
Syntax
tf = issparse(A)Inputs
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
A | Any | Yes | — | Input value to test. |
Returns
| Name | Type | Description |
|---|---|---|
tf | LogicalArray | True when input is a sparse matrix. |
Errors
| Identifier | When | Message |
|---|---|---|
RunMat:issparse:InternalError | Resident handle ownership or dtype metadata is contradictory. | issparse: invalid resident metadata |
How issparse works
issparse(sparse(...))returnstrue.- Empty sparse matrices such as
sparse(m,n)returntrue. - Dense numeric tensors, scalar numbers, logical values, strings, character arrays, cells, structs, objects, and function handles return
false. - Dense
gpuArrayhandles returnfalse; RunMat does not currently expose native sparse GPU storage. - The result is always a logical scalar.
GPU memory and residency
issparse does not gather dense GPU tensors; it returns false for gpuArray handles because RunMat sparse matrices are host-resident.
Examples
Sparse matrix predicate
S = sparse([1 3], [1 2], [4 -1], 3, 2);
tf = issparse(S)Expected output:
tf =
1Dense arrays are not sparse
A = [0 4; 0 0];
tf = issparse(A)Expected output:
tf =
0Full conversion clears sparse storage
S = sparse(3, 2);
A = full(S);
[issparse(S), issparse(A)]Expected output:
ans = [1 0]Using issparse with coding agents
Open a RunMat example with live inputs, then ask the agent to explain how issparse changes the result.
Run a small issparse example, explain the result, then change one input and compare the output.
FAQ
Does issparse inspect the number of zeros?⌄
No. It reports the storage representation. A dense matrix full of zeros returns false, while an empty sparse matrix returns true.
Are gpuArray values sparse?⌄
No. RunMat's current gpuArray representation is dense, so issparse(gpuArray(A)) returns false.
Does issparse return an array for array inputs?⌄
No. Like MATLAB, it returns one logical scalar describing the input value.
Related Logical functions
Open-source implementation
Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how issparse is executed, line by line, in Rust.
- View the source for issparse in Rust on GitHub
- Learn how the RunMat runtime works
- Found a bug? Open an issue with a minimal reproduction.
About RunMat
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