vsip_vcreate_kaiser_p - Create a Kaiser Window Vector

Core

This manual is preliminary and incomplete.
While our Core implementation implements all functions given in the standard we are still working on completing this documentation.

Please refer to the VSIPL standard for a complete function reference of the Core profile until we have completed work on this documentation.

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5.3.2 vsip_vcreate_kaiser_p - Create a Kaiser Window Vector

vsip_vview_f* vsip_vcreate_kaiser_f(vsip_length n, vsip_scalar_f beta, vsip_memory_hint hint);

Description

This function creates and initializes a vector with coefficients of a Kaiser window of length $n$ . The Kaiser window is defined by:

( ) √︂ --(2k----)2 I0 β 1- n-1-1 w[k]= -----------------, 0≤ k< n I0(β)

where $I0$ is the zeroth-order modified Bessel function of the first kind.

Parameters

vsip_length n: Length of the window (number of elements in the vector).
vsip_scalar_p beta: Shape parameter that controls the trade-off between main lobe width and side lobe attenuation, $β$ .
vsip_memory_hint hint: Memory allocation hint:
- VSIP_MEM_NONE - No memory hint
- VSIP_MEM_RDONLY - The memory is to be used read-only
- VSIP_MEM_CONST - The memory will hold constants
- VSIP_MEM_SHARED - The memory will be shared
- VSIP_MEM_SHARED_RDONLY - The memory will be shared and is read-only
- VSIP_MEM_SHARED_CONST - The memory will be shared and will hold constants

Return Value

On success, returns a pointer to the newly created and initialized vector containing the Kaiser window coefficients.
On error, returns NULL.

Example

vsip_vview_f *kaiser_win; 
vsip_length n = 64; 
vsip_scalar_f beta = 6.0f;  // Moderate side lobe suppression 
 
// Create a Kaiser window 
kaiser_win = vsip_vcreate_kaiser_f(n, beta, VSIP_MEM_NONE); 
 
if (kaiser_win == NULL) { 
    // Handle error 
} 
 
// Use the window in an application 
// For example, apply it to a signal 
vsip_vview_f *signal = vsip_vcreate_f(n, VSIP_MEM_NONE); 
vsip_vview_f *windowed_signal = vsip_vcreate_f(n, VSIP_MEM_NONE); 
 
// Initialize signal... 
// vsip_vramp_f(0.0f, 1.0f, signal); 
 
// Apply the window 
vsip_vmul_f(signal, kaiser_win, windowed_signal); 
 
// Clean up 
vsip_valldestroy_f(kaiser_win); 
vsip_valldestroy_f(signal); 
vsip_valldestroy_f(windowed_signal);

Notes

The Kaiser window is symmetric for even-length vectors and nearly symmetric for odd-length vectors.
Common $β$ values and their approximate side lobe attenuations:
- $β =0$ : Rectangular window ( 13 dB)
- $β =3$ : 30 dB side lobe attenuation
- $β =6$ : 50 dB side lobe attenuation
- $β =8.6$ : 60 dB side lobe attenuation

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