not — Compute element-wise logical negation in MATLAB and RunMat.

not(X) inverts the logical interpretation of each element in X. Truthiness conversion and output shape follow MATLAB semantics.

Syntax

tf = not(A)

Inputs

Returns

Errors

How not works

• Works on scalars, vectors, matrices, and N-D tensors with MATLAB broadcasting semantics.
• Accepts logical, numeric, complex, and character arrays. Character code points equal to zero become true, all others become false.
• Returns a logical scalar when the input has exactly one element; otherwise the result is a logical array matching the input shape.
• Honors gpuArray residency. If the active acceleration provider exposes logical_not, the entire operation runs on the GPU; otherwise RunMat falls back to the CPU path automatically.
• NaN evaluates to true, so not(NaN) produces false, consistent with MATLAB.

Does RunMat run not on the GPU?

When RunMat Accelerate is active, not dispatches to the provider hook logical_not. Providers write 0 or 1 into a device buffer, keeping the result resident on the GPU. If the provider does not implement the hook, RunMat gathers the input to host memory, executes the CPU implementation, and (if the caller passed a gpuArray) returns a logical array on the host so the call never fails.

GPU memory and residency

You usually do not have to call gpuArray manually. RunMat's auto-offload planner moves data to the GPU when a fused expression benefits from device execution. The not builtin preserves existing residency; results remain on the GPU until you gather them or another operation requires host access. Use gpuArray when porting MATLAB code that already does so explicitly or when you want to pin tensors to the GPU ahead of time.

Examples

Checking if a scalar value is zero

result = not(5)

Expected output:

result =
     0

Negating a logical mask to find the complement

mask = [true false true];
inverseMask = not(mask)

Expected output:

inverseMask =
  1×3 logical array
     0     1     0

Turning nonzero numeric entries into false values

A = [0 1 2 0];
B = not(A)

Expected output:

B =
  1×4 logical array
     1     0     0     1

Flipping zero and nonzero character codes

chars = ['A' 0 'C'];
flags = not(chars)

Expected output:

flags =
  1×3 logical array
     0     1     0

Performing logical NOT directly on the GPU

G = gpuArray([0 4 0 9]);
deviceResult = not(G);
hostResult = gather(deviceResult)

Expected output:

deviceResult =
  1×4 gpuArray logical array
     1     0     1     0
hostResult =
  1×4 logical array
     1     0     1     0

Using not with coding agents

Open a RunMat example with live inputs, then ask the agent to explain how not changes the result.

FAQ

Related Logical functions

Open-source implementation

Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how not is executed, line by line, in Rust.

• View the source for not 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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