5.2.8 vsip_dcorrelate1d_p - Compute 1D Correlation

typedef enum _visp_bias { 
  VSIP_BIASED   = 0, 
  VSIP_UNBIASED = 1 
} vsip_bias; 
 
void vsip_correlate1d_f(const vsip_corr1d_f *cor, vsip_bias bias, const vsip_vview_f *h, const vsip_vview_f *x, const vsip_vview_f *y); 
void vsip_ccorrelate1d_f(const vsip_ccorr1d_f *cor, vsip_bias bias, const vsip_cvview_f *h, const vsip_cvview_f *x, const vsip_cvview_f *y);

Description

This function computes the one-dimensional correlation between an input signal and a reference signal using the pre-configured correlation object. The result is stored in the output vector . The correlation operation computes:

The exact form depends on the support region specified when creating the correlation object and the bias option.

Parameters

• const vsip_dcorr1d_p* cor: Pointer to the 1D correlation object created with vsip_dcorr1d_create_p .

• vsip_bias bias: Bias option for the correlation:

  • VSIP_NOBIAS: No bias applied

  • VSIP_BIASED: Bias applied (normalization)

• const vsip_dvview_p* h: Reference signal vector of length .

• const vsip_dvview_p* x: Input signal vector of length .

• const vsip_dvview_p* y: Output correlation vector. Its length depends on the support region specified in the correlation object.

Example

vsip_corr1d_f *corr; 
vsip_vview_f *h, *x, *y; 
vsip_length m = 1024;  // Input signal length 
vsip_length n = 64;    // Reference signal length 
vsip_length y_len;     // Output length 
 
// Create correlation object for full correlation 
corr = vsip_corr1d_create_f(m, n, VSIP_SUPPORT_FULL, 100, VSIP_ALG_TIME); 
if (corr == NULL) { 
    fprintf(stderr, "Error: Could not create correlation object\n"); 
    return; 
} 
 
// Determine output length based on support region 
vsip_corr1d_attr_f attr; 
vsip_corr1d_getattr_f(corr, &attr); 
y_len = (attr.support == VSIP_SUPPORT_FULL) ? m + n - 1 : 
       (attr.support == VSIP_SUPPORT_SAME) ? m : 
       abs(m - n) + 1; 
 
// Create vectors 
h = vsip_vcreate_f(n, VSIP_MEM_NONE);      // Reference signal 
x = vsip_vcreate_f(m, VSIP_MEM_NONE);      // Input signal 
y = vsip_vcreate_f(y_len, VSIP_MEM_NONE);  // Output correlation 
 
// Initialize reference and input signals 
// vsip_vramp_f(0.0f, 1.0f, h);  // Example: linear ramp for reference 
// vsip_vramp_f(0.0f, 0.5f, x);  // Example: linear ramp for input 
 
// Compute correlation without bias 
vsip_correlate1d_f(corr, VSIP_NOBIAS, h, x, y); 
 
// Compute correlation with bias (normalized) 
vsip_correlate1d_f(corr, VSIP_BIASED, h, x, y); 
 
// Clean up 
vsip_corr1d_destroy_f(corr); 
vsip_valldestroy_f(h); 
vsip_valldestroy_f(x); 
vsip_valldestroy_f(y);

Notes

• The input vectors and must have lengths matching those specified when the correlation object was created.

• The output vector must have the appropriate length based on the support region:

  • VSIP_SUPPORT_FULL:

  • VSIP_SUPPORT_SAME:

  • VSIP_SUPPORT_MIN:

• The bias option affects the normalization of the result:

  • VSIP_NOBIAS: No normalization applied

  • VSIP_BIASED: Result is normalized