Hilbert

Computes a complex analytic signal dst, which contains the original real signal src as its real part, and computed Hilbert transform as its imaginary part. The Hilbert transform is performed according to the spec specification parameters: the number of samples len and hint. The input data is zero-padded or truncated to the size of len.

The Hilbert function calling process is as follows:

Initialize the HmppsHilbertPolicy_32f structure by calling Init.
Call the main function.
Call Release to release the memory contained in the HmppsHilbertPolicy_32f function.

The function interface is declared as follows:

Initialization:
HmppResult HMPPS_HilbertInit_32f32fc(int32_t len, HmppsHilbertPolicy_32f32fc **policy);
Main function:
HmppResult HMPPS_Hilbert_32f32fc(const float *src, Hmpp32fc *dst, int32_t len, HmppsHilbertPolicy_32f32fc *policy);
Memory release:
HmppResult HMPPS_HilbertRelease_32f32fc(HmppsHilbertPolicy_32f32fc *policy);

Parameters

Parameter	Description	Value Range	Input/Output
src	Source vector	Not null	Input
dst	Destination vector	Not null	Output
len	Vector length	(0, INT_MAX]	Input
policy (in the Init function)	Double pointer to HmppsHilbertPolicy	Not null	Output
policy (in the main and release functions)	Pointer to the HmppsHilbertPolicy structure	Not null	Input

Return Value

Success: HMPP_STS_NO_ERR
Failure: An error code is returned.

Error Codes

Error Code	Description
HMPP_STS_NO_ERR	No error occurs.
HMPP_STS_NULL_PTR_ERR	Any of the specified pointers is null.
HMPP_STS_SIZE_ERR	The value of len is less than or equal to 0.
HMPP_STS_MALLOC_FAILED	The Init function failed to allocate the memory required by the algorithm model.
HMPP_STS_MISMATCH	The size of the problem that the Init function applies for memory does not match the size of the problem that is actually calculated in the main function.

Note

Before this interface is called for calculation, the Init interface must be called to initialize the HmppsHilbertPolicy_32f standard structure.
The initialization of the HmppsHilbertPolicy_32f structure must be applied for in the Init function. You cannot apply for or define this structure by yourself.

Example

void Hilbert_Example()
{
    const int len = 10;
    float src[len];
    Hmpp32fc dst[len];
    HmppsHilbertPolicy_32f32fc *policy = NULL;

    for (int i = 0; i < 10; ++i){
        src[i] = i / 10.0;
    }
    HmppResult result = HMPPS_HilbertInit_32f32fc(len, &policy);
    if (result != HMPP_STS_NO_ERR) {
        return;
    }
    result = HMPPS_Hilbert_32f32fc(src, dst, len, policy);
    if (result != HMPP_STS_NO_ERR) {
        return;
    }
    result = HMPPS_HilbertRelease_32f32fc(policy);
    if (result != HMPP_STS_NO_ERR) {
        return;
    }
    for (int i = 0; i < len; ++i) {
        printf("%.2f + %.6fi ", dst[i].re, dst[i].im);
    }

}

Output:

0 + 0.550553i, 0.1 + -0.0649839i, 0.2 + -0.0649839i, 0.3 + -0.210292i, 0.4 + -0.210292i, 0.5 + -0.210292i, 0.6 + -0.210292i, 0.7 + -0.0649839i, 0.8 + -0.0649839i, 0.9 + 0.550553i,

Parent topic: Transform Algorithms