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StdDev

Calculates the standard deviation of a vector.

The calculation formula is as follows:

The function interface declaration is as follows:

  • Operations on floating-point numbers:

    HmppResult HMPPS_StdDev_32f(const float *src, int32_t len, float *stdDev, HmppHintAlgorithm hint);

    HmppResult HMPPS_StdDev_64f(const double *src, int32_t len, double *stdDev);

  • Scaling of integers:

    HmppResult HMPPS_StdDev_16s_S(const int16_t *src, int32_t len, int16_t *stdDev, double scale);

    HmppResult HMPPS_StdDev_16s32s_S(const int16_t *src, int32_t len, int32_t *stdDev, double scale);

Parameters

Parameter

Description

Value Range

Input/Output

src

Pointer to the source vector

The value cannot be NULL.

Input

len

Vector length

(0, INT_MAX]

Input

stdDev

Pointer to the standard deviation

The value cannot be NULL.

Output

hint

Algorithm policy

HmppAlgHintNone, HmppAlgHintFast, HmppAlgHintAccurate

Input

scale

Scale factor

scale = 2^n, where n is an integer. The value is within (0, INF).

Input

Return Value

  • Success: HMPP_STS_NO_ERR
  • Failure: An error code is returned.

Error Codes

Error Code

Description

HMPP_STS_NULL_PTR_ERR

The value of src or stdDev is NULL.

HMPP_STS_SIZE_ERR

The value of len is less than or equal to 0.

HMPP_STS_SCALE_ERR

The value of scale is not within the range (0, INF) or is NaN.

Example

#define BUFFER_SIZE_T 10

void StdDevExample(void)
{
    float src[BUFFER_SIZE_T] = {4.58, 0.98, 4.30, 8.03, 11.19, 8.41, 4.55, 9.90, 0.14, 9.59};
    float dst;
    HmppHintAlgorithm hint = HMPP_ALGHINT_NONE;

    HmppResult result = HMPPS_StdDev_32f(src, BUFFER_SIZE_T, &dst, hint);
    printf("stdDev: result = %d ", result);
    if (result != HMPP_STS_NO_ERR) {
        return;
    }
    printf("stdDev = %.2f\n", dst);
}

Output:

stdDev: result = 0 stdDev = 3.82