Window.c File Reference

Prototypes
static REAL4Window *	XLALREAL4Window_from_REAL8Window (REAL8Window *orig)
	Constructs a REAL4Window from a REAL8Window by quantizing the double-precision data to single-precision. More...
static double	Y (int length, int i)
	Maps the length of a window and the offset within the window to the "y" co-ordinate of the LAL documentation. More...
static REAL8	sum_squares (REAL8 *start, int length)
	Computes the sum of squares, and sum, of the samples in a window function. More...
static REAL8	sum_samples (REAL8 *start, int length)
REAL8Window *	XLALCreateREAL8WindowFromSequence (REAL8Sequence *sequence)
	Constructs a new REAL8Window from a REAL8Sequence. More...
REAL4Window *	XLALCreateREAL4WindowFromSequence (REAL4Sequence *sequence)
	Single-precision version of XLALCreateREAL8WindowFromSequence(). More...
REAL8Sequence *	XLALUnitaryWindowREAL8Sequence (REAL8Sequence *sequence, const REAL8Window *window)
	Multiply a REAL8Sequence in-place by a REAL8Window with a normalization that preserves the variance of a zero-mean stationary Gaussian random process. More...
COMPLEX16Sequence *	XLALUnitaryWindowCOMPLEX16Sequence (COMPLEX16Sequence *sequence, const REAL8Window *window)
	Double-precision complex version of XLALUnitaryWindowREAL8Sequence(). More...
REAL4Sequence *	XLALUnitaryWindowREAL4Sequence (REAL4Sequence *sequence, const REAL4Window *window)
	Single-precision version of XLALUnitaryWindowREAL8Sequence(). More...
COMPLEX8Sequence *	XLALUnitaryWindowCOMPLEX8Sequence (COMPLEX8Sequence *sequence, const REAL4Window *window)
	Single-precision complex version of XLALUnitaryWindowREAL8Sequence(). More...
REAL8Window *	XLALCreateRectangularREAL8Window (UINT4 length)
REAL8Window *	XLALCreateHannREAL8Window (UINT4 length)
REAL8Window *	XLALCreateWelchREAL8Window (UINT4 length)
REAL8Window *	XLALCreateBartlettREAL8Window (UINT4 length)
REAL8Window *	XLALCreateParzenREAL8Window (UINT4 length)
REAL8Window *	XLALCreatePapoulisREAL8Window (UINT4 length)
REAL8Window *	XLALCreateHammingREAL8Window (UINT4 length)
REAL8Window *	XLALCreateKaiserREAL8Window (UINT4 length, REAL8 beta)
REAL8Window *	XLALCreateCreightonREAL8Window (UINT4 length, REAL8 beta)
REAL8Window *	XLALCreateTukeyREAL8Window (UINT4 length, REAL8 beta)
REAL8Window *	XLALCreateGaussREAL8Window (UINT4 length, REAL8 beta)
REAL8Window *	XLALCreateLanczosREAL8Window (UINT4 length)
void	XLALDestroyREAL8Window (REAL8Window *window)
REAL4Window *	XLALCreateRectangularREAL4Window (UINT4 length)
REAL4Window *	XLALCreateHannREAL4Window (UINT4 length)
REAL4Window *	XLALCreateWelchREAL4Window (UINT4 length)
REAL4Window *	XLALCreateBartlettREAL4Window (UINT4 length)
REAL4Window *	XLALCreateParzenREAL4Window (UINT4 length)
REAL4Window *	XLALCreatePapoulisREAL4Window (UINT4 length)
REAL4Window *	XLALCreateHammingREAL4Window (UINT4 length)
REAL4Window *	XLALCreateKaiserREAL4Window (UINT4 length, REAL4 beta)
REAL4Window *	XLALCreateCreightonREAL4Window (UINT4 length, REAL4 beta)
REAL4Window *	XLALCreateTukeyREAL4Window (UINT4 length, REAL4 beta)
REAL4Window *	XLALCreateGaussREAL4Window (UINT4 length, REAL4 beta)
REAL4Window *	XLALCreateLanczosREAL4Window (UINT4 length)
void	XLALDestroyREAL4Window (REAL4Window *window)
static int	XLALParseWindowNameAndCheckBeta (const char *windowName, REAL8 beta)
	Parse window-name string (case-insensitive) into an internal window-type index (>=0, returned), and also check if the user-input 'beta' is valid for given window. More...
int	XLALCheckNamedWindow (const char *windowName, const BOOLEAN haveBeta)
	Check whether a named window-function exists and whether it requires a parameter. More...
REAL8Window *	XLALCreateNamedREAL8Window (const char *windowName, REAL8 beta, UINT4 length)
	Generic window-function wrapper, allowing to select a window by its name. More...
REAL4Window *	XLALCreateNamedREAL4Window (const char *windowName, REAL8 beta, UINT4 length)

Go to the source code of this file.

Enumerations
enum	LALWindowType {   LAL_WINDOWTYPE_RECTANGULAR = 0 , LAL_WINDOWTYPE_HANN , LAL_WINDOWTYPE_WELCH , LAL_WINDOWTYPE_BARTLETT ,   LAL_WINDOWTYPE_PARZEN , LAL_WINDOWTYPE_PAPOULIS , LAL_WINDOWTYPE_HAMMING , LAL_WINDOWTYPE_KAISER ,   LAL_WINDOWTYPE_CREIGHTON , LAL_WINDOWTYPE_TUKEY , LAL_WINDOWTYPE_GAUSS , LAL_WINDOWTYPE_LANCZOS ,   LAL_WINDOWTYPE_LAST }

Variables
struct {
const char *const   name
	window name More...
const BOOLEAN   hasBeta
	does this window need a 'beta' parameter? More...
}	AllowedWindows [LAL_WINDOWTYPE_LAST]

Enumeration Type Documentation

LALWindowType

enum LALWindowType

Enumerator
LAL_WINDOWTYPE_RECTANGULAR
LAL_WINDOWTYPE_HANN
LAL_WINDOWTYPE_WELCH
LAL_WINDOWTYPE_BARTLETT
LAL_WINDOWTYPE_PARZEN
LAL_WINDOWTYPE_PAPOULIS
LAL_WINDOWTYPE_HAMMING
LAL_WINDOWTYPE_KAISER
LAL_WINDOWTYPE_CREIGHTON
LAL_WINDOWTYPE_TUKEY
LAL_WINDOWTYPE_GAUSS
LAL_WINDOWTYPE_LANCZOS
LAL_WINDOWTYPE_LAST

Definition at line 774 of file Window.c.

Function Documentation

XLALREAL4Window_from_REAL8Window()

static REAL4Window* XLALREAL4Window_from_REAL8Window ( REAL8Window *  orig )

static

Constructs a REAL4Window from a REAL8Window by quantizing the double-precision data to single-precision.

The REAL8Window is freed unconditionally. Intended to be used as a wrapper, to convert any function that constructs a REAL8Window into a function to construct a REAL4Window.

Definition at line 58 of file Window.c.

Y()

static double Y ( int  length, int  i  )

static

Maps the length of a window and the offset within the window to the "y" co-ordinate of the LAL documentation.

Input: length > 0, 0 <= i < length

Output: length < 2 --> return 0.0 i == 0 --> return -1.0 i == (length - 1) / 2 --> return 0.0 i == length - 1 --> return +1.0

e.g., length = 5 (odd), then i == 2 --> return 0.0 if length = 6 (even), then i == 2.5 --> return 0.0

(in the latter case, obviously i can't be a non-integer, but that's the value it would have to be for this function to return 0.0)

Definition at line 109 of file Window.c.

sum_squares()

static REAL8 sum_squares ( REAL8 *  start, int  length  )

static

Computes the sum of squares, and sum, of the samples in a window function.

Two techniques are employed to achieve accurate results. Firstly, the loop iterates from the edges to the centre. Generally, window functions have smaller values at the edges and larger values in the middle, so adding them in this order avoids adding small numbers to big numbers. The loops also implement Kahan's compensated summation algorithm in which a second variable is used to accumulate round-off errors and fold them into later iterations.

Definition at line 128 of file Window.c.

sum_samples()

static REAL8 sum_samples ( REAL8 *  start, int  length  )

static

Definition at line 158 of file Window.c.

XLALParseWindowNameAndCheckBeta()

static int XLALParseWindowNameAndCheckBeta ( const char *  windowName, REAL8  beta  )

static

Parse window-name string (case-insensitive) into an internal window-type index (>=0, returned), and also check if the user-input 'beta' is valid for given window.

Window-types that don't take a beta input parameter need to have beta==0.

Returns XLAL_FAILURE=-1 on error

Definition at line 819 of file Window.c.

Variable Documentation

name

const char* const name

window name

Definition at line 792 of file Window.c.

hasBeta

const BOOLEAN hasBeta

does this window need a 'beta' parameter?

Definition at line 793 of file Window.c.

const { ... } AllowedWindows[LAL_WINDOWTYPE_LAST]

Initial value:

= {
 
  [LAL_WINDOWTYPE_RECTANGULAR]  = { "rectangular",      0 },
  [LAL_WINDOWTYPE_HANN]         = { "hann",             0 },
  [LAL_WINDOWTYPE_WELCH]        = { "welch",            0 },
  [LAL_WINDOWTYPE_BARTLETT]     = { "bartlett",         0 },
  [LAL_WINDOWTYPE_PARZEN]       = { "parzen",           0 },
  [LAL_WINDOWTYPE_PAPOULIS]     = { "papoulis",         0 },
  [LAL_WINDOWTYPE_HAMMING]      = { "hamming",          1 },
  [LAL_WINDOWTYPE_KAISER]       = { "kaiser",           1 },
  [LAL_WINDOWTYPE_CREIGHTON]    = { "creighton",        1 },
  [LAL_WINDOWTYPE_TUKEY]        = { "tukey",            1 },
  [LAL_WINDOWTYPE_GAUSS]        = { "gauss",            1 },
  [LAL_WINDOWTYPE_LANCZOS]      = { "lanczos",          0 },
}