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Reference guides are available for functions and commands supported by OML, Tcl, and Python.
Reference Guide for OpenMatrix Language Functions
The Reference Guide contains documentation for all functions supported in the OpenMatrix language.
Control System Commands
isdt
Returns true if an LTI model is in discrete time.

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- Scripting Guide for OpenMatrix Language
  OpenMatrix is a mathematical scripting language.
- Reference Guide for OpenMatrix Language Functions
  The Reference Guide contains documentation for all functions supported in the OpenMatrix language.
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    - acker
      Ackermann's formula (pole placement gain selection for single-input systems).
    - append
      Appends the inputs and outputs of the two models.
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      Add states to the outputs of a state-space model.
    - balreal
      Computes a Gramian balanced realization of an LTI model.
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      Block diagonalization with the Schur factorization.
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      Builds a block diagonal matrix with the input parameters.
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      Bode diagram.
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      Computes a discrete-time state-space model from a continuous-time state-space model.
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      Solves the continuous-time Algebraic Riccati Equation.
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      Steady-state co-variance.
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      Controllability matrix.
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      Calculates the controllability staircase form.
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      Converts a discrete model to continuous time model.
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      Compute natural frequencies, damping ratios, and poles.
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      Solves the Discrete-time Algebraic Riccati Equations.
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      Transforms decibels (dB) to magnitude.
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      Low-frequency (DC) gain of a state-space or transfer function model
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      Linear-quadratic regulator for a discrete-time model.
    - dlyap
      Solve discrete-time Lyapunov or Sylvester equations.
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      Solves discrete-time Lyapunov equations with a square-root solver.
    - dss
      Constructs a descriptor state-space model.
    - dss2ss
      Converts a descriptor state-space system into regular state-space form.
    - dssdata
      Extracts data from a descriptor state-space model.
    - esort
      Sorts continuous-time poles in descending order by the real component.
    - estim
      Returns the state estimator for a given estimator gain.
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      Compute the matrix exponential.
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      Constructs a transfer function model in DSP format.
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      Generates an input signal for the lsim function.
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      Computes the observability and controllability Gramians.
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      Hankel singular values of a state-space or transfer function model.
    - impulse
      Compute the impulse response of a control system.
    - isct
      Returns true if the LTI model is in continuous time.
    - isctrb
      Returns true if the state-space model is controllable.
    - isdt
      Returns true if an LTI model is in discrete time.
    - isobsv
      Returns true if the state-space is observable.
    - issiso
      Checks if an LTI model is single-input/single-output (SISO)
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      Checks if an LTI model is stable or unstable
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      Kalman filter or estimator.
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      Matrix logarithm.
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      Linear quadratic estimator (Kalman Filter)
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      Linear-quadratic regulator for a continuous-time model.
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      Calculates the optimal steady-state feedback gain matrix K.
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      Simulates LTI model response to arbitrary inputs.
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      Solves continuous Lyapunov or Sylvester equations.
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      Solves continuous-time Lyapunov equation using a square-root solver.
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      Computes magnitude from decibels (dB).
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      Margin stability.
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      Minimal realization.
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      Nyquist diagram.
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      Returns the observability matrix of a state-space model.
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      Calculates the observability staircase form.
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      Computes the Pade approximation of time delays.
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      Connects two state-space or transfer functions in parallel.
    - pid
      Constructs a continuous-time PID controller transfer function.
    - place
      Pole assignment.
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      Compute poles for a state-space or transfer function model.
    - prescale
      Scale a state-space model.
    - reg
      Creates a state regulator with specified state-feedback and estimator gains.
    - rlocfind
      Find gain and poles for specific points of a root locus diagram.
    - rlocus
      rlocus diagram.
    - rsf2csf
      Transforms a real Schur form to a complex Schur form.
    - series
      Connects two state-space or transfer function in a series.
    - sqrtm
      Matrix square root.
    - ss
      Constructs a state-space model.
    - ss2ss
      Transforms a state-space model to another state-space model.
    - ss2tf
      Converts state-space model parameters to transfer function model parameters.
    - ss2tfc
      Convert state-space model parameters to transfer function model parameters.
    - ssdata
      Extracts data from a state-space model.
    - step
      Compute the step response of a control system.
    - tf
      Constructs a transfer function model
    - tf2ss
      Transforms transfer function parameters to state-space parameters.
    - tf2ssc
      Transforms transfer function parameters to state-space parameters.
    - tf2zp
      Transforms (continuous) transfer function parameters to zero-pole-gain parameters.
    - tf2zpk
      Transforms (discrete) transfer function parameters to zero-pole-gain parameters.
    - tfdata
      Extracts data from a transfer function model.
    - zp2ss
      Zero-pole to state-space conversion.
    - zp2tf
      Zero-pole to transfer function conversion.
    - zpk
      Constructs a zero, pole, gain model.
    - zpkdata
      Extracts data from a zero-pole-gain model.
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Frequently Asked Questions
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isdt

Returns true if an LTI model is in discrete time.

Syntax

BRES = isdt(sys)

Inputs

sys: An LTI model.

Outputs

BRES: A Boolean true if it is discrete.

Examples

For a discrete-time system:

Gz = tf(4.47, [1 -4.43], -1);
isdt(Gz)

ans = 1

For a continuous time system:

Gz = tf(4.47, [1 -4.43]);
isdt(Gz)

ans = 0

Comments

Returns true if an LTI model is in discrete time.