MAL.Acceleration

ref_arr_out = MAL.Acceleration( [BYREF arr_out      AS ARRAY],

                                 BYREF arr_in       AS ARRAY,

                                [BYVAL nLength      AS INTEGER=2],

                                [BYVAL nPoint       AS INTEGER=ML_ALL],

                                [BYVAL nFrameOffset AS INTEGER=0] ) AS REFERENCE

Calculates the acceleration of the data supplied in the input array.  The nLength parameter determines the number of frames it skips over for the acceleration calculation.  This creates a way of applying a smoothing filter to the data.  The longer the length, the smoother the data.  The default is 2, meaning it's skipping 1 sample for each calculation. See table below.  Since acceleration is the 2nd derivative, it calculates the velocity first before it calculates the acceleration.

To set the Frame rate  (fequency) used to calculate the acceleration, call the MAL.FrameRate function.

Table Showing Frames used with nLength 2

Example:

OPTION EXPLICIT ON

OPTION BASE 1

' Include C3D Support

$INCLUDE "MyBASIC2_C3DFile"

$LIBRARY "MyBASIC2_C3DFileLib"

' Needed to extract and Display Version

$LIBRARY "MyBASIC2_ExtLib"

' Include the MaxMAL Library

$INCLUDE "MyBASIC2_MaxMAL"

$LIBRARY "MyBASIC2_MaxMALLib"

' Forward Declare PrintArray and DisplayVersion

DECLARE SUB PrintArray

DECLARE SUB DisplayVersion

' Declare variables and arrays

DIM nPoints AS INTEGER

DIM nFrames AS INTEGER

DIM hFile   AS INTEGER

' Test File

CONST cFileName = "e:\walk8.c3d"

' Display the current Library Version

CALL DisplayVersion()

' Open the Test File

hFile = C3DFile.Open( cFileName )

IF NOT hFile > 0 THEN

  PRINT "Error Opening File ";cFileName,

  STOP

ENDIF

' Get the no of points and frames

nFrames = C3DFile.GetNoOfFrames( hFile )

nPoints = C3DFile.GetNoOfPoints( hFile )

' Dimension the arrays

DIM Position(nFrames,nPoints,3)    AS REAL

DIM Velocity(nFrames,nPoints,3)     AS REAL

DIM Acceleration(nFrames,nPoints,3) AS REAL

' Get the Point Coordinates from C3D file

IF C3DFile.GetPoints( hFile, Position ) <> nFrames THEN

  C3DFile.Close( hFile )

  PRINT "Error Reading ";nPoints;" from file ";cFileName,

  STOP

ENDIF

' Set the Frame Rate to use in the MaxMAL Library

MAL.FrameRate( C3DFile.GetFrameRate( hFile ) )

' Display the Position Coordinates

CALL PrintArray( REF( Position ) )

' Calculate and Display Velocity

MAL.Velocity( Velocity, Position )

CALL PrintArray( REF( Velocity ) )

' Calculate and Display Acceleration

MAL.Acceleration( Acceleration, Position )

CALL PrintArray( REF( Acceleration ) )

' Close File

C3DFile.Close( hFile )

END

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''

' Print an array with up to 3 dimensions.  Array is passed as a reference

'

SUB PrintArray( arr AS REFERENCE )

  RUN( "ArrayTable", arr, TRUE )

END SUB

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''

' Display the MaxMAL Extension Library Version

'

SUB DisplayVersion()

  DIM major AS INTEGER

  DIM minor AS INTEGER

  DIM build AS INTEGER

  DIM qfe   AS INTEGER

  major = BYTE.HI( WORD.HI( MAL.Version() ) )

  minor = BYTE.LO( WORD.HI( MAL.Version() ) )

  build = BYTE.HI( WORD.LO( MAL.Version() ) )

  qfe   = BYTE.LO( WORD.LO( MAL.Version() ) )

  PRINT "Library Version: ";FORMAT( "%d, %d, %d, %d", major, minor, build, qfe ),

  PRINT "Option Flags:    ";FORMAT( "0x%08X", MAL.Version( TRUE ) ),

END SUB