Variance

void riscv_var_f16(const float16_t *pSrc, uint32_t blockSize, float16_t *pResult)

void riscv_var_f32(const float32_t *pSrc, uint32_t blockSize, float32_t *pResult)

void riscv_var_f64(const float64_t *pSrc, uint32_t blockSize, float64_t *pResult)

void riscv_var_q15(const q15_t *pSrc, uint32_t blockSize, q15_t *pResult)

void riscv_var_q31(const q31_t *pSrc, uint32_t blockSize, q31_t *pResult)
 group variance
Calculates the variance of the elements in the input vector. The underlying algorithm used is the direct method sometimes referred to as the twopass method:
There are separate functions for floating point, Q31, and Q15 data types.
Functions

void riscv_var_f16(const float16_t *pSrc, uint32_t blockSize, float16_t *pResult)
Variance of the elements of a floatingpoint vector.
 Parameters
pSrc – [in] points to the input vector
blockSize – [in] number of samples in input vector
pResult – [out] variance value returned here
 Returns
none

void riscv_var_f32(const float32_t *pSrc, uint32_t blockSize, float32_t *pResult)
Variance of the elements of a floatingpoint vector.
 Parameters
pSrc – [in] points to the input vector
blockSize – [in] number of samples in input vector
pResult – [out] variance value returned here
 Returns
none

void riscv_var_f64(const float64_t *pSrc, uint32_t blockSize, float64_t *pResult)
Variance of the elements of a floatingpoint vector.
 Parameters
pSrc – [in] points to the input vector
blockSize – [in] number of samples in input vector
pResult – [out] variance value returned here
 Returns
none

void riscv_var_q15(const q15_t *pSrc, uint32_t blockSize, q15_t *pResult)
Variance of the elements of a Q15 vector.
 Scaling and Overflow Behavior
The function is implemented using a 64bit internal accumulator. The input is represented in 1.15 format. Intermediate multiplication yields a 2.30 format, and this result is added without saturation to a 64bit accumulator in 34.30 format. With 33 guard bits in the accumulator, there is no risk of overflow, and the full precision of the intermediate multiplication is preserved. Finally, the 34.30 result is truncated to 34.15 format by discarding the lower 15 bits, and then saturated to yield a result in 1.15 format.
 Parameters
pSrc – [in] points to the input vector
blockSize – [in] number of samples in input vector
pResult – [out] variance value returned here
 Returns
none

void riscv_var_q31(const q31_t *pSrc, uint32_t blockSize, q31_t *pResult)
Variance of the elements of a Q31 vector.
 Scaling and Overflow Behavior
The function is implemented using an internal 64bit accumulator. The input is represented in 1.31 format, which is then downshifted by 8 bits which yields 1.23, and intermediate multiplication yields a 2.46 format. The accumulator maintains full precision of the intermediate multiplication results, and as a consequence has only 16 guard bits. There is no saturation on intermediate additions. If the accumulator overflows it wraps around and distorts the result. In order to avoid overflows completely the input signal must be scaled down by log2(blockSize)8 bits, as a total of blockSize additions are performed internally. After division, internal variables should be Q18.46 Finally, the 18.46 accumulator is right shifted by 15 bits to yield a 1.31 format value.
 Parameters
pSrc – [in] points to the input vector
blockSize – [in] number of samples in input vector
pResult – [out] variance value returned here
 Returns
none

void riscv_var_f16(const float16_t *pSrc, uint32_t blockSize, float16_t *pResult)