`hour` — Extract hour components from datetime values in MATLAB and RunMat.

hour(dt) extracts hour-of-day values from datetime scalars or arrays and returns doubles with matching shape. Extraction behavior follows MATLAB semantics.

Syntax

X = hour(t)

Inputs

Name	Type	Required	Default	Description
`value`	`Any`	Yes	—	Datetime input.

Returns

Name	Type	Description
`X`	`Any`	Numeric scalar/tensor result.

Errors

Identifier	When	Message
`RunMat:datetime:InvalidArgument`	Arguments or option grammar do not match supported datetime forms.	`datetime: invalid argument`
`RunMat:datetime:InvalidInput`	Input values cannot be parsed/converted/broadcast to a valid datetime result.	`datetime: invalid input`
`RunMat:datetime:Internal`	Internal datetime state or indexing/evaluation failed unexpectedly.	`datetime: internal operation failed`

How `hour` works

hour(t) accepts datetime scalars and datetime arrays.
The output shape matches the input shape.
Hour values are returned in 24-hour clock form.
Passing a non-datetime value raises a datetime-specific error.

Does RunMat run `hour` on the GPU?

hour does not dispatch GPU kernels; it extracts the hour component from CPU-side datetime objects.

GPU memory and residency

No. hour reads datetime objects on the CPU and returns ordinary host-side numeric arrays.

Examples

Extract the hour from a scalar datetime

t = datetime(2024, 4, 9, 13, 30, 5);
h = hour(t)

Expected output:

h = 13

Extract hours from a datetime array

t = datetime([2024 2024], [4 4], [9 9], [8 17], [15 45], [0 0]);
h = hour(t)

Expected output:

h =
     8    17

Using `hour` with coding agents

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

Run a small hour example, explain the result, then change one input and compare the output.

FAQ

What clock convention does hour use?⌄

It returns 24-hour clock values such as 0, 13, or 23.

Does hour preserve the input shape?⌄

Yes. The numeric output has the same size as the input datetime array.

Does hour run on the GPU?⌄

No. datetime values are host-side objects, so hour executes on the CPU.

datetime · day · duration · minute · month · second · year

Open-source implementation

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

View the source for hour 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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hour — Extract hour components from datetime values in MATLAB and RunMat.