all — Test whether all elements are nonzero along a dimension in MATLAB and RunMat.

all(X) returns logical true when every element in the selected slice of X is nonzero. By default, all reduces along the first non-singleton dimension; optional dim, "all", and nanflag arguments follow MATLAB semantics.

Syntax

B = all(A)
B = all(A, dim)
B = all(A, "all")
B = all(A, nanflag)
B = all(A, dim, nanflag)
B = all(A, nanflag, dim)

Inputs

Returns

Errors

How all works

• Works with logical, numeric, complex, and character arrays; other types raise a descriptive error.
• Accepts all(X, dim) to reduce along a single dimension or all(X, vecdim) to collapse multiple axes at once.
• all(X, 'all') flattens the entire array into a single logical scalar.
• all(___, 'omitnan') ignores NaN values (including complex parts) when deciding whether a slice contains nonzero content; empty or all-NaN slices evaluate to true.
• all(___, 'includenan') (default) treats NaN as logical true, matching MATLAB behaviour.
• Empty dimensions yield logical ones with MATLAB-compatible shapes; empty arrays reduced with 'all' return true.
• Results are always host-resident logical scalars or logical arrays, even when the input tensor lives on the GPU, because the runtime copies the compact output back to the CPU.

Does RunMat run all on the GPU?

RunMat Accelerate keeps inputs resident on the GPU whenever possible. Providers that expose reduce_all_dim (and optionally reduce_all) perform the AND-reduction on device buffers, and the runtime then downloads the tiny logical result back to the CPU. When those hooks are missing, RunMat gathers the input tensor and evaluates the reduction on the host instead, preserving MATLAB behaviour in all cases.

GPU memory and residency

You usually do not need to call gpuArray manually. The fusion planner keeps GPU-resident inputs on the device and only gathers the small logical results that all produces. If your workload already uses explicit gpuArray/gather calls for MATLAB compatibility, RunMat honours them and still produces correct logical outputs.

Examples

Checking if every column is nonzero

A = [1 2 3; 4 5 6];
colAllNonZero = all(A)

Expected output:

colAllNonZero = [1 1 1]

Verifying that each row contains only nonzero values

B = [1 0 3; 4 5 6; 0 7 8];
rowAllNonZero = all(B, 2)

Expected output:

rowAllNonZero = [0; 1; 0]

Collapsing multiple dimensions with vecdim

C = reshape(1:24, [3 4 2]);
allAlongDims = reshape(all(C > 0, [1 2]), 1, 2)

Expected output:

1 1

Reducing all elements to a single logical scalar

D = [2 4; 6 8];
everythingNonZero = all(D, 'all')

Expected output:

everythingNonZero = true

Ignoring NaN values while testing slices

E = [NaN 1 2; NaN 0 3];
withNaN = all(E);               % returns [1 0 1]
ignoringNaN = all(E, 'omitnan'); % returns [1 0 1]
disp(withNaN);
disp(ignoringNaN)

Expected output:

1 0 1
1 0 1

Evaluating all on GPU arrays

G = gpuArray([1 1 1; 1 1 1]);
gpuResult = all(G, 2);     % RunMat returns a host logical array
disp(gpuResult)

Expected output:

1
1

Testing all with character arrays

chars = ['a' 0 'c'];
allPrintable = all(chars);
disp(allPrintable)

Expected output:

0

Using all with coding agents

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

FAQ

Related Math functions

Open-source implementation

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

• View the source for all in Rust on GitHub
• Learn how the RunMat runtime works
• Found a bug? Open an issue with a minimal reproduction.

About RunMat

RunMat is an open-source runtime that executes MATLAB-syntax code blazing on any GPU. It is licensed under the Apache 2.0 license.

• RunMat automatically optimizes your math for GPU execution on Apple, Nvidia, and AMD hardware. No code changes needed. Simulations that took hours now take minutes.
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