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Hold

Discrete

Sample-and-hold block that samples the input at regular intervals and holds or interpolates the value between samples.

Mathematical Model

Zero-Order Hold (ZOH):

y(t) = u(t_k) \quad \text{for } t_k \le t < t_{k+1}

First-Order Hold (FOH):

y(t) = u(t_k) + (u(t_k) - u(t_{k-1}))/T · (t - t_k)  for t_k ≤ t < t_{k+1}

where t_k = k · T and T is the sample time.

Direction	ID	Label	Type	Status
→ In	`in`	In	number	Required
← Out	`out`	Out	number	Output

Parameters	Label	Type	Default	Description
`mode`	Hold Mode	select	`zoh`
`sampleTime`	Sample Time	number	`0.01`

Zie de ingebouwde voorbeelden in de handleiding voor een demonstratie van dit blok.

ZOH vs FOH: Zero-Order Hold produces a staircase output (common in DACs); First-Order Hold linearly extrapolates (smoother but can overshoot)
Sample time: Must be ≥ the simulation base timestep; values below the base step are clamped
Rate transition: Use Hold to bridge subsystems running at different sample rates
ZOH mode: Most numerically stable; recommended unless FOH's smoother output is explicitly needed
FOH mode: Requires two prior samples; initial behaviour differs on the first step after a rate transition