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API, Reference Guides
Overview of external readers and the Altair Binary Format, the generic ASCII reader, running applications in batch mode, using Tcl/Tk commands, translators, and result math.
Templex and Math Reference Guide
Math Reference
Mathematical functions and operators, including syntax, operators and specific information about each function.
Functions and Operators
Overview of functions and operators.
External Functions
List of external functions.
th_butter
Four-pole Butterworth filter.

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API, Reference Guides
Overview of external readers and the Altair Binary Format, the generic ASCII reader, running applications in batch mode, using Tcl/Tk commands, translators, and result math.
- Extensions
  Extensions are programs integrated with the application to enhance or extend the user experience.
- External Readers and Altair Binary Format
  Altair Binary Format (ABF) is the standard binary format read by the program. A library called abflib allows you to create files in ABF.
- Generic ASCII Reader
  A generic ASCII reader is now available which allows you to bring custom results directly into HyperView. The Altair ASCII format is useful for reading the results of any in-house or propriety codes which are saved in a generic format.
- Batch Mode
  Batch mode allows you perform a series of operations outside the program interface.
- External Resources
  External resources can be registered in preference files, session files, or Templex files. If an external resource is registered in a program session, it is automatically registered in the session file when the session is saved.
- Python API
  The Python API documentation for HyperMesh applications.
- Tcl/Tk Commands
  The application's scripting interface is a set of Tcl/Tk commands that follow a simple and consistent syntax.
- Translators
  Translators are utilities that are run from the command line of the operating system to convert various types of files into different formats.
- Result Math
  XML commands in the Result Math Module.
- HWC Console
  Record playback workflows in the application.
- HyperMesh Report
- Task Manager
  Use the Task Manager to load an XML file that defines tasks and their attributes.
- HyperMesh
- MotionView
- Templex and Math Reference Guide
  - Templex Reference
    Templex is a general purpose text and numeric processor which generates output text based on guidelines defined in a template.
  - Math Reference
    Mathematical functions and operators, including syntax, operators and specific information about each function.
    - Data Types
      The mathematical functions accept arguments of different data types.
    - Order of Precedence
      The standard mathematical order of operations is followed when an expression is evaluated.
    - Functions and Operators
      Overview of functions and operators.
      - Operators
        List of operators.
      - Standard Functions
        List of standard functions.
      - External Functions
        List of external functions.
        barchart (bar)
        Creates a bar chart representation of selected data.
        besselfilteranalog
        Applies the analog Bessel filter on the input signal.
        besselfilterdigital
        Applies a digital Bessel filter on the input signal.
        butterworth (bwfilt)
        Filters data forward and backward using a second order Butterworth algorithm.
        clip
        The 3ms criterion commonly used to measure potential for chest injury.
        clip_continuous
        The 3ms criterion commonly used to measure potential for chest injury.
        clip_cumulative
        The 3ms criterion commonly used to measure potential for chest injury.
        duration
        Calculates the cumulative duration for response values, given the X and Y input data vectors. The duration will be partitioned into 100 segments.
        fir100
        Performs 100 Hz finite impulse response filtering of a digitized time series.
        fuse
        Removes overlaps in curves.
        hic
        The Head Injury Criterion commonly used to measure potential for head injury.
        hicd
        Modified Head Injury Criterion for use with the free-motion head form.
        histogram
        Creates a simplified histogram representation of selected data.
        iso6487
        SAE J211/1 revision MAR95 filter with ISO 6487 compliant mirroring applied.
        kth
        nee-thigh-hip injury function.
        levelcrossing
        Signal processing tool that extracts equivalent constant amplitude fatigue cycles from a time series of load or strain data.
        nij
        Calculate the Neck Injury Criteria.
        rainflow
        Reduces the number of vector points from the test data without losing the damage, magnitude, and/or effect of the test data.
        rangepair
        Reduces the number of vector points from the test data without losing the damage, magnitude, and/or effect of the test data.
        saefilt95
        SAE J211/1 revision MAR95 compliant filter.
        th_bandpass_butter
        Four-pole Butterworth filter.
        th_butter
        Four-pole Butterworth filter.
        th_cfc
        Channel Frequency Class filter.
        th_fir100
        Fir100 filter.
        th_four
        Low Pass Fourier filter.
        th_sae
        SAE class filter.
        th_tche
        Tchebychev class filter.
        timeatlevel
        Signal processing tool that indicates how long the signal spends at a given magnitude.
        Effects of Sampling Interval and Signal Length
        Since the Nyquist frequency is half the sampling frequency, a higher sampling frequency will yield a spectrum in a wider frequency band.
    - Signal Processing
      Overview of Fast Fourier Transform, phenomena, windowing, Filtering Frequency Response, functions, blocking, and Hilbert Transform.
- Script and Model Library
  The Script and Model Library is a database of freely accessible scripts and models posted by users and Altair engineers.

th_butter

Four-pole Butterworth filter.

Syntax

th_butter(xvect, yvect, lowfreq, octave, debug_flag)

Arguments

xvect: The time vectors (seconds).
yvect: Response vectors to be filtered (any units).
lowfreq: Low Frequency (Hz).
octave: Can be 3 or 6.
debug_flag: Optional argument. Flag to turn on debug mode (points to message log). Default is off.

Example

th_butter(p1w1c1.x, p1w1c1.y, 0.02, 6)

Comments

4−pole Butterworth filter is a low−pass filter, which means that high frequencies are filtered.

Equivalent filters in TH++ are:

LOW PASS 4-poles Butterworth (-3db)
LOW PASS 4-poles Butterworth (-6db)