or — Compute element-wise logical OR across scalar or array inputs with MATLAB-compatible expansion.

or(A, B) returns logical true where either operand is nonzero, using MATLAB-compatible implicit expansion and logical conversion rules.

Syntax

tf = or(A, B)

Inputs

Returns

Errors

How or works

• MATLAB-compatible mode accepts logical and real numeric arrays, including every integer class with exact zero/nonzero truth semantics. RunMat compatibility mode additionally accepts complex and character arrays.
• Supports MATLAB-style implicit expansion so scalars and singleton dimensions broadcast automatically.
• Propagates empty dimensions: if a broadcasted axis has length 0, the output is an empty logical array with the same shape.
• Treats NaN values as true, matching MATLAB's element-wise logical semantics.
• Uses a validated floating logical_or hook when available. Native integer handles bypass floating hooks and gather exactly; automatic residency may return to host, while explicit gpuArray inputs restore a logical gpuArray result.

Does RunMat run or on the GPU?

When both operands reside on the GPU and the active provider implements the logical_or hook, RunMat lowers the call into a device kernel that writes 0 or 1 for each element. The fusion planner treats or as an element-wise operation, so fused expressions (for example, or(A > 0, B)) stay on device without intermediate gathers. If the provider lacks the hook, the runtime gathers the inputs to host memory automatically and executes the CPU implementation instead of failing.

GPU memory and residency

You usually do not need to call gpuArray explicitly. RunMat's native auto-offload logic moves data to the GPU when a fused expression benefits from device execution, and results stay resident until you gather them or the planner needs host access. Call gpuArray only when you want to seed residency manually, or when you are porting MATLAB code that already uses explicit device transfers.

Examples

Check if either logical scalar is true

result = or(true, false)

Expected output:

result =
     1

Combine numeric arrays element-wise with logical OR

A = [1 0 2 0];
B = [3 4 0 0];
C = or(A, B)

Expected output:

C =
  1×4 logical array
     1     1     1     0

Apply logical OR with automatic scalar expansion

mask = [1; 0; 3; 0];
flag = or(mask, 0)

Expected output:

flag =
  4×1 logical array
     1
     0
     1
     0

Use logical OR with character arrays

lhs = ['R' 'u' 0];
rhs = ['R' 0 'n'];
match = or(lhs, rhs)

Expected output:

match =
  1×3 logical array
     1     1     1

Run logical OR directly on the GPU

G1 = gpuArray([0 2 0 4]);
G2 = gpuArray([1 0 3 0]);
deviceResult = or(G1, G2)
hostResult = gather(deviceResult)

Expected output:

deviceResult =
  1×4 gpuArray logical array
     1     1     1     1
hostResult =
  1×4 logical array
     1     1     1     1

Using or with coding agents

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

FAQ

Related Logical functions

Open-source implementation

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

• View the source for or 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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