isvector — Test whether values are vectors in MATLAB and RunMat.

isvector(A) returns true when A is 1-by-N or N-by-1 (including scalars). Dimensionality rules across value types follow MATLAB semantics.

Syntax

tf = isvector(A)

Inputs

Returns

How isvector works

• isvector is true for 1-by-N and N-by-1 arrays (with N ≥ 0), including scalars (1×1).
• Arrays with more than two dimensions always return false, even when all trailing dimensions are singleton (for example, 1×1×1).
• Empty arrays follow MATLAB rules: size 0×1 or 1×0 is a vector, but size 0×3 is not.
• Character arrays, string arrays, cell arrays, structs, objects, and handle objects follow the same dimension check.
• GPU tensors use metadata stored in their GpuTensorHandle. If metadata is missing, RunMat gathers once to inspect dimensions.
• Sparse matrices currently follow dense semantics; when sparse support lands, isvector will continue to rely on reported dimensions.

Does RunMat run isvector on the GPU?

isvector never launches GPU kernels. For gpuArray inputs the builtin first inspects the shape metadata on the GpuTensorHandle. If a provider omits that metadata, RunMat downloads the tensor once to obtain it and then computes the result on the host. The builtin always returns a host logical scalar, so fusion planning treats it as a metadata query instead of a device-side kernel.

GPU memory and residency

isvector performs its checks on whatever residency the input already uses. It will happily accept a GPU tensor without the caller moving it to the CPU first, because the builtin only needs the tensor's metadata. When a provider fully populates tensor shapes (as the WGPU provider does), the runtime never downloads the data. If metadata is missing, the runtime gathers once to recover the shape and then continues on the host. Users can still call gpuArray for compatibility with MathWorks MATLAB, but it is not required for this builtin.

Examples

Checking if a row vector input is a vector

tf = isvector([1 2 3])

Expected output:

tf = logical(1)

Detecting that a matrix is not a vector

tf = isvector([1 2 3; 4 5 6])

Expected output:

tf = logical(0)

Verifying that a scalar counts as a vector

tf = isvector(42)

Expected output:

tf = logical(1)

Handling empty dimensions exactly like MATLAB

tf_zero_col = isvector(zeros(1,0));
tf_zero_row = isvector(zeros(0,1));
tf_zero_by_three = isvector(zeros(0,3))

Expected output:

tf_zero_col = logical(1)
tf_zero_row = logical(1)
tf_zero_by_three = logical(0)

Working with character and string arrays

tf_char = isvector('RunMat');
tf_string_row = isvector(["a","b","c"])

Expected output:

tf_char = logical(1)
tf_string_row = logical(1)

Confirming GPU tensor metadata without gathering

G = gpuArray((1:5)');
tf_gpu = isvector(G)

Expected output:

tf_gpu = logical(1)

Rejecting higher-dimensional arrays

tf = isvector(ones(1,1,4))

Expected output:

tf = logical(0)

Trailing singleton dimensions are still rejected

tf = isvector(ones(1,1,1))

Expected output:

tf = logical(0)

Using isvector with coding agents

Open a RunMat example with live inputs, then ask the agent to explain how isvector changes the result.

FAQ

Related Array functions

Open-source implementation

Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how isvector is executed, line by line, in Rust.

• View the source for isvector 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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